
"3 

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Copyright^ . 



COPYRIGHT DEPOSIT. 



Digitized by the Internet Archive 
in 2011 with funding from 
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DIEMAKING AND 
DIE DESIGN 



DIEMAKING AND 
DIE DESIGN 



A TREATISE ON THE DESIGN AND PRAC- 
TICAL APPLICATION OF DIFFERENT CLASSES 
OF DIES FOR BLANKING, BENDING, FORM- 
ING AND DRAWING SHEET-METAL PARTS, 
INCLUDING MODERN DIEMAKING PRACTICE 
AND FUNDAMENTAL PRINCIPLES OF DIE 
CONSTRUCTION 



COMPILED AND EDITED 

By FRANKLIN D. JONES 

Associate Editor of MACHINERY 

Author of " Turning and Boring," " Planing 

and Milling," " Gaging Tools and 

Methods," Etc. 



FIRST EDITION 



NEW YORK 

THE INDUSTRIAL PRESS 

London: THE MACHINERY PUBLISHING CO., Ltd. 
1915 



Copyright, 1915 

BY 

THE INDUSTRIAL PRESS 

NEW YORK 



,3 






Composition and Eledrotyping by 
F. H. Gilson Company, Boston, U.S.A. 



GI.A410964 



PREFACE 

Dies are now used so extensively and have made possible 
such wonderful results in the rapid production of sheet-metal 
parts, that die construction has become a subject of great 
importance to everyone interested in modern manufacturing 
methods. This treatise deals with the two essential elements in 
the production of dies; namely, the designing of various types, 
and the methods of constructing them. It also includes a great 
deal of information on the practical application of different 

classes of dies. 

In any kind of machine or tool manufacture there is always 
some variation in the methods employed in different machine 
shops and tool-rooms for doing the same general class of work, 
and diemakers are not an exception to this universal rule. In 
fact, there is probably a greater difference in the methods of die- 
makers than is found in any other single branch of tool or ma- 
chine manufacture, because of the almost endless variety of dies 
which has often made it necessary for diemakers to devise their 
own methods of procedure. Therefore, this treatise contains 
information which, to some extent, represents the practice and 
experience of different diemakers, and while, in some cases, 
there may be other and, perhaps, better methods for accomplish- 
ing the same results, an effort has been made to deal with funda- 
mental principles and present information that is not only reliable, 
but of practical value to those engaged in this kind of work. 

Throughout the book various types of dies are described to 
illustrate practical designs. All of these designs are special in 
the sense that they are intended for producing some particular 
part, and, at first thought, it might seem useless to study the 
details of a die which in all probability will not exactly be dupli- 
cated within the experience of any one toolmaker or diemaker. 



vi . PREFACE 

It should be remembered, however, that the best way to obtain 
a broad, general knowledge of die construction is by studying as 
many different designs as possible in order to become familiar 
with those features which have proved successful in actual 
practice. Incidentally, many of the tools illustrated are in- 
genious types and represent, in a general way, what has been 
accomplished in the art of constructing dies. 

Readers of mechanical literature are familiar with Ma- 
chinery's twenty-five cent Reference Books, of which one 
hundred and forty-one different titles have been published dur- 
ing the past seven years. As many subjects cannot be covered 
adequately in all their phases in books of this size, and in response 
to a demand for more comprehensive and detailed treatments 
of the more important mechanical subjects, it has been deemed 
advisable to publish a number of larger volumes, of which this 
is one. This treatise includes part of Machinery's Reference 
Books Nos. 126, 131 and 132, and it is believed to be unusually 
complete in its treatment of the more important branches of 
die work. 

F. D. J. 

New York, August, 1915. 



CONTENTS 



Chapter I 
CLASSES OF DIES FOR SHEET-METAL WORK 



Pages 



Plain Blanking Dies — Follow or Progressive Dies — 
Gang or Multiple Dies — Compound Dies — Perforating 
Dies — Shaving or Trimming Dies — Burnishing Dies — 
Embossing Dies — Drawing Dies, including the Combina- 
tion, Double-action, and Triple-action Types — Redrawing 
Dies — Forming Dies — Bending Dies — Curling Dies — 
The Sub-press Type of Die — Swaging Dies 1-24 



Chapter II 

DIEMAKING METHODS AND BLANKING DIE 
CONSTRUCTION 

Kinds of Steel Used for Die Work — Value of Annealing — 
Laying Out Blanking Dies — Laying Out Dies for Washers 

— Templets for Blanking Dies — How a Templet is Used — - 
Methods of Machining Blanking Dies — Die Shaping, Slot- 
ting and Milling Machines — Filing Dies by Hand — Die- 
filing Machine — Clearance between Punches and Dies for 
Different Thicknesses of Stock — Angular Die Clearance — 
Fitting the Punch to the Die — Methods of Holding Punches 

— Types of Piercing Punches — Locating Punches in Punch- 
holder — Shear of Punches and Dies — Hardening Punches 
and Dies — Reworking Worn Dies — Stripping Stock from 
Punch — ■ Cam-actuated Strippers — Pilots or Guide Pins for 
Punches — Punch Troubles and Remedies — Various Types 
of Stop-pins for Controlling Feeding Movement of Stock — 
Position of Stop-pin Relative to Hole in Die — Various 

Types of Die-beds or Bolsters — Examples of Blanking Dies 25-108 



viii CONTENTS 

Chapter III 
DRAWING AND FORMING DIES 

Pages 

Selecting Type of Drawing Die — Depth of First Drawing 
Operation — Diameter of First Drawing Die — Diameter 
Reductions for Redrawing — Formation of Wrinkles — 
Shapes of Drawing Edges — Ironing or Thinning the Stock 

— How to Determine the Blank Diameter — Blank Diame- 
ter Formulas for Various Shapes of Drawn Shells — Forma- 
tion of Air Pockets in Dies — Lubricants for Drawing — 
Examples of Drawing Die Design — Drawing Cartridge 
Cases — Drawing Brass Shrapnel Cases — Multiple Draw- 
ing Die of Indexing Type — Dies for Rectangular Drawing 

— Blank-holder Pressure Compensating Attachment — Lay- 
ing Out Rectangular Dies — Shape of Blanks for Rectangular 
Work — Blanks for Drawing Elliptic Shapes — Trimming 
Drawn Rectangular Parts — Miscellaneous Points on Draw- 
ing and Forming Die Construction 109-187 

Chapter IV 

BENDING AND CURLING DIES 

Simple Types of Bending Dies — Die for Making Four 
Bends — Die for Making Five Bends — Staple Bending Die 
— Combination Bending and Twisting Die — Compound 
Bending Die — Curling Dies for Hinges — Curling Dies for 
Tin Buckets — Special Curling Die — Wiring Dies for Small 
Brass Covers 1 88-2 1 1 

Chapter V 

CONSTRUCTION AND USE OF SUB-PRESS DIES 

Advantages of the Sub-press — Typical Sub-press Die Con- 
struction — Sub-press Die for Blanking and Forming Copper 
Cups — Large Sub-press Dies — Sectional Sub-press Die — 
Making Sub-press Dies — Sub-press Die of the Four-post 
Type — Stripping Blanks that Adhere to Punches and 
Ejectors — Separating Sub-press Die Blanks from Scrap. . . 212-243 



CONTENTS IX 

Chapter VI 
SECTIONAL PUNCH AND DIE CONSTRUCTION 

Pages 

Advantages of the Sectional Type — Examples of Sectional 
Die Construction — Sectional Die for Square Washers — 
Sectional Die for Linotype Type-bar Plates — Making Sec- 
tional Die Parts — Grinding Die Sections — Special Chucks 
for Holding Die and Punch Sections — Milling Segments for 
Pole-piece Sectional Punches 244-264 



Chapter VII 

AUTOMATIC FEEDING AND EJECTING MECHANISMS 

FOR PRESSES 

The Single-roll Feed — Automatic Release for Feed-rolls 

— Rack and Pinion Double-roll Feed — Push Feed — Slide 
Feed — Ratchet Dial Feed — Friction Dial Feed — Friction 
Dial and Push Feed — Friction Dial and Reciprocating Feed 

— Chute and Hopper Feed — Feed Chute for Drawing Press 

— Mechanically-operated Knockout — Ejecting Press Work 

with Air Blast 265-286 



Chapter VIII 

TOOLS FOR PERFORATING CYLINDRICAL AND 
CONICAL WORK 

Construction of Perforating Dies — Perforating Shells of 
Tapered and Irregular Shapes — Methods of Rotating Shell 
to be Perforated — Lay-out of a Perforating Die — Making 
the Punch for a Perforating Die — The Stripper of a Per- 
forating Die — Spiral Perforating — Tools for Perforating 
Brass Shells 287-313 



X . CONTENTS 

Chapter IX 
MULTIPLE PLUNGER PRESS AND ITS TOOLS 

Pages 

Arrangement of a Typical Multiple Plunger Press — 
Transfer Slide and Auxiliary Mechanism — Operation of the 
Transfer Slide — Methods of Holding the Punches and Dies 
- Tools for Multiple Plunger Presses — Examples of Shell 
Work Done on Multiple Plunger Press — Strippers for Mul- 
tiple Plunger Press Work — Examples of Flanged Shell Work 
— Drawing Operation on Eight-plunger Press 314-329 



DIEMAKING AND DIE DESIGN 



CHAPTER I 
CLASSES OF DIES FOR SHEET-METAL WORK 

It is rather difficult to classify and give proper definitions of 
the many designs and types of dies used on power presses for 
the production of sheet-metal work. While there are, of course, 
some general classes into which all dies may be divided, the 
various types overlap in many cases, so that one is often in 
doubt as to the proper classification of dies which combine the 
features of different types. All dies may, in the first place, be 
divided into two general classes, viz., cutting dies, and shaping 
dies. Cutting dies include all designs which simply cut or 
punch flat blanks or pieces of the required outline from the stock 
fed into the press. On the other hand, shaping dies include all 
those which change the form of the material from its original 
flat condition. This second main division, however, often in- 
cludes features which are common to the first; that is, some 
dies are a combination of cutting and shaping dies, the blank to 
be shaped or formed being first cut out to the required outline 
from the stock and then shaped to the desired form. 

The main classes of dies, as will be seen, are based on the use 
of the die. The first of the classes mentioned, cutting dies, may, 
however, be further sub-divided according to the construction 
of the various types of dies in this class. We then distinguish 
between four distinct types, viz., plain blanking dies, follow dies, 
multiple or gang dies, and compound dies. The second main 
division of shaping dies cannot be sub-divided according to the 
construction of the dies in the same manner as the cutting dies. 
Owing to the great variety of work performed in shaping dies, 
the designs vary too greatly for a classification on the basis of 



CLASSES OF DIES 



constructional features. They may, however, be divided into 
sub-classes arranged according to the general uses to which they 
are put; thus, there are bending dies, embossing and forming 
dies, drawing dies, and curling dies. 

These different classes of cutting and shaping dies are briefly 
described in the following to indicate, in a general way, the 
constructional features and practical application of each type. 
In succeeding chapters more detailed descriptions are given, and 
a variety of the more important classes of dies are illustrated. 

Plain Blanking Dies. — Plain blanking dies are the simplest of 
all types of dies and are used to cut out plain, flat pieces of 



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PLAN OF DIE Machinery 



Fig. i. Plain Blanking Punch and Die 

stock having, in general, no perforations. This type of die con- 
sists of a die-block D (see Fig. i), which has an opening that 
conforms to the shape of the part to be cut or blanked out; a 
punch block P, which accurately fits the opening in the die- 
block and, by a shearing action, does the cutting as it descends 
into the die-block opening; and a stripper plate S, which strips 
the stock off of the punch block as the latter ascends. The 
opening in the stripper plate conforms to the shape of the punch 
and is either slightly larger to provide a little clearance, or close 
fitting to steady the punch. Between the stripper plate and 
die-block there is a guide G, which serves to keep the stock in 
alignment with the die opening as it is fed along. This guide 
(which may be formed by planing a channel on the under side of 
the stripper) is made so that the space between the die and strip- 



BLANKING DIES 3 

per will be somewhat greater than the thickness of the stock used; 
in fact, this space must be sufficient to allow the stock to move 
along easily even when the surface is made somewhat irregular 
by the operation of the punch. In a simple die of this kind, the 
spacing of the holes punched in the stock is commonly con- 
trolled by some form of stop-pin A, which engages the edge of 
each successive opening; for instance, after a blank is cut out, 
the operator feeds the stock along until the opening thus made 
comes against the stop, thus locating the stock for cutting out 
the next blank. 

Follow Dies. — Follow dies are used for work which must be 
cut from the stock to the required shape and, at the same time, 




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Fig. 2. Follow Die for Piercing and Blanking Washer 

be provided with holes or perforations. The principle of the 
follow die is that while one part of the die punches the hole in 
the stock, another part blanks out the work at a place where, at 
a former stroke, a hole or opening was punched, so that a com- 
pleted article results from each stroke of the press; in reality, 
however, two separate operations have been performed, the 
operation being a progressive one in which the holes are first 
pierced after which the stock moves along until the pierced 
section is in line with the blanking punch. A simple form of 
follow die designed for cutting washers is shown in Fig. 2. The 



4 CLASSES OF DIES 

blanking punch is located at B and the piercing punch at C. 
As the stock is fed along in the direction indicated by the arrow 
(see plan view of die) the hole in the washer is first made by the 
piercing punch; then, on the next stroke of the press, the stock 
is fed a distance x so that the pierced hole is directly under the 
blanking punch, which cuts out the completed washer. The 
action of the two punches relative to the stock is indicated at 
A which illustrates a small section of the stock. As both punches 
operate at the same time, obviously, a completed washer is cut 
out at each stroke of the press. Of course, if the washers were 
required in large quantities, the die would be designed to cut 
out two or more washers at each stroke of the press. 

Many dies of this type have a pilot D on the end of the 
blanking punch which engages the pierced hole after the stock 
has been approximately located by a stop-pin, or otherwise. In 
this way, the stock is located so that the outside is cut con- 
centric with the hole, within a small limit of variation. When 
the blanking punch is without a pilot, the accuracy of the work 
is dependent upon the accuracy with which the stock is fed 
through the die. For instance, if an operator should fail to 
push the stock against the stop-pin, the cut made by the blank- 
ing punch would not be correctly located relative to the pierced 
hole. Hence, pilots are commonly used, although they have 
one objectionable feature: If the punch should descend when 
the pierced hole was not under the pilot, a broken punch might 
result, unless a spring-supported pilot, which could recede, were 
employed. Even when a pilot is used, extremely accurate work 
cannot be produced in a follow die because there must be a 
slight clearance between the pilot and the pierced hole and this 
causes more or less error; moreover, when using a die of the 
design illustrated in Fig. 2, the stock is distorted or wrinkled 
to some extent by the action of the punches because the stock 
lies loosely between the stripper and the die. To avoid this 
trouble, some blanking dies have a spring-supported stripper 
which is attached to the punch and presses against the stock 
while the punches are at work. Some punch presses are also 
equipped with a cam-actuated stripper. 



BLANKING DIES 



Follow dies are also called "progressive" or "tandem" dies. 
They are also frequently termed "gang" dies, although it is 
doubtful if the latter name is correct. (See Gang or Multiple 
Dies.) By referring to Fig. 2, it will be seen that the blanking 
punch is slightly longer than the piercing punch. This is done 
in order that the pilot may engage the hole in the stock and 
locate it before the piercing punch comes into action. 

Gang or Multiple Dies. — When large numbers of blanks are 
required, multiple or gang dies are sometimes used. These dies 
have a number of duplicate punches with similar openings 
in the die-block and cut as many blanks as there are punches, 
at each stroke of the press. Fig. 3 illustrates a simple form of 



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Fig. 3. Gang or Multiple Die 

gang or multiple die. As will be seen, there are, in this case, 
three blanking punches. At the first stroke of the press, the 
stock is blanked out as at A ; then, by feeding it a distance x for 
each stroke, the blank will be cut as at B. As will be noted, the 
punches in this case are located twice the center-to-center dis- 
tance between the openings cut in the stock, instead of being 
close together. This is done because it would not be practi- 
cable to have the openings in the die-block as close as they 
should be in order to blank out the stock economically, since 
there would not be metal enough between the die openings to 
insure sufficient strength. The term " gang die " is often applied 



6 CLASSES OF DIES 

to a follow die; this usage is generally conceded to be incorrect, 
however, as the word "gang," as used in mechanics, ordinarily 
means a combination of similar tools so arranged as to act 
simultaneously for producing duplicate parts. 

Compound Dies. — Compound dies differ from plain blanking 
and follow dies in that the simple punch and die elements are 
not separated but are combined so that both the upper and 
the low members contain what corresponds to a punch and 
die, as well as suitable stripper plates or ejectors. The faces of 



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Machinery 



Fig. 4. Compound Die which Pierces and Blanks Simultaneously 

the punches, dies, and stripper plates are normally held at 
about the same level and the strippers are spring supported so 
as to recede when the stock is being cut. A compound die pro- 
duces more accurate work than the types previously referred to 
for the reason that all operations are carried out simultaneously 
at one stroke, while the stock is firmly held between the spring 
supported stripper plates and opposing die-faces. A compound 
die is shown in Fig. 4. The operation of this die is as follows: 
The upper die descends and depresses stripper plate C. As the 
downward movement continues, the blank is cut from the stock 



BLANKING DIES 7 

by members A and B and, at the same time, a central hole is 
pierced by punch D, as indicated by the right-hand view. The 
blank is forced out of the upper die B by ejector E as the ram 
ascends, and the stripper plate C also pushes the stock up off 
of the die-block A. The scrap punched from the hole falls 
through the opening in die-block A, which has clearance to 
provide a free passage-way. The blank is returned to the 
strip of stock, from which it can easily be removed. 

Inasmuch as the piercing and blanking operations are per- 
formed at the same time, very accurate work can be obtained 
in a die of the compound type. Such delicate parts as armed 
wheels or gear punchings for clocks, meters, etc., are examples 
of the work that can be done in this form of die. Such parts 
are made complete, including the arm spaces, center hole, and 
holes in the arms or rim if desired, with one stroke of the press. 
The stock from the arm spaces and other holes is forced down 
through the die while the blank is returned to the strip from 
which it was punched. The punchings obtained in a compound 
die are flat, accurate as to size, shape, and position of holes, and 
can be made very rapidly. One method of using a die of the 
compound type is to fit the punch into the socket of the slide 
of the press, and, after aligning, to clamp the die-block to 
the bolster plate. This method is fairly satisfactory for simple 
punches and dies, but, with more complicated designs, the align- 
ing is more difficult and it is also more necessary that it should 
be as perfect as possible; hence a better arrangement is needed 
and this has been found in the sub-press method (see The 
Sub-press) . 

Perforating Dies. — The dies used for punching large numbers 
of holes or perforations in sheet metal, for producing strainers, 
sifting devices, etc., and also the dies used for cutting orna- 
mental shapes around the edges of lamp-burner shells, etc., are 
commonly known as perforating dies. The type of die used for 
perforating sheet stock is in reality a multiple or gang die, but 
as a general rule the work of a perforating die differs from a 
gang die in that it is used to punch a large number of holes, 
whereas a gang or multiple die, as these names are ordinarily 



8 



CLASSES OF DIES 



applied, means the type that is used to blank out a number 
of duplicate parts. There may be exceptions, however, to this 
general classification. Some perforating dies, such as are used 
for perforating sheet metal or other materials, have hundreds 
of punches which are arranged in rows and operate simulta- 
neously. 

Shaving Dies. — Dies of this class are sometimes used for 
finishing the edges of comparatively thick blanks which have 
been cut out in a regular blanking die. A blanking die used for 
cutting heavy stock must have a certain amount of clearance 
between the punch and die opening, the amount depending 



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Machinery 



Fig. 5. Simple Design of Shaving or Trimming Die 

upon the thickness and kind of material. As the result of this 
clearance (which lessens the danger of breaking the punch and 
reduces the pressure required for the punching operation), the 
edges of thick blanks are somewhat rough and also tapering, as 
shown at A, Fig. 5. To secure smooth square edges, shaving 
dies are used in some cases. The plan view to the left illustrates 
a simple form of shaving die designed for finishing the blank, 
shown at B. This die has an opening which conforms to the 
shape required for the finished blank and it is equipped with 
two arms e and / which are pivoted at g and h, respectively. 



SHAVING DIES 9 

These arms are notched to receive and locate the rough blank 
directly over the die opening. In the operation of the die, the 
arms are swung outward as indicated by the dotted lines, and 
are then closed in on the blank and against the locating pins /. 
The press is then tripped and the punch (which fits the hole in 
the die) descends and pushes the blank through the die, thus 
shaving and finishing the rough edges. 

Shaving dies do not always have pivoted arms to locate or 
form a "nest" for the blank, but are sometimes provided with 
movable plates which are held in position by springs and have 
beveled edges so that they are forced outward slightly each time 
a blank is pushed downward through the die. Spring pins are 
also used to form a nest in shaving dies. The advantage of 
movable arms or a nest supported laterally by springs is that they 
not only facilitate inserting and removing the blank, but pre- 
vent the chips from jamming between the blank and the nest, 
as they tend to do with a nest of the fixed type. The pivoted 
arms or movable plates also facilitate cleaning away the chips 
from the top of the die face. Incidentally, it is very important, 
when making a blanking die for parts which are to be pushed 
through a shaving die afterwards, to have the right amount of 
play or clearance between the blanking punch and die. When 
there is not the right amount of clearance, the edges of the blank 
will be too ragged and irregular or, as the diemaker would ex- 
press it, the blank is not cut with a "clean break"; the result is 
that these irregularities make it impossible to secure a smooth 
edge by means of the shaving die. 

Sometimes the entire edge or contour of a blank does not 
need to be finished but it is necessary to have part of the sur- 
face smooth. In such a case, the effect of shaving may be 
obtained in the blanking die, and without a separate shaving 
operation, by piercing a hole adjacent to the edge where a good 
finish is required. The principle of this method is illustrated 
at C, Fig. 5. Assuming that it is only necessary to have the 
curved edge n (see sketch B) smooth, hole m should be pierced 
in the stock adjacent to edge n, prior to the blanking operation, 
by means of a piercing punch. The result is that, when the 



IO 



CLASSES OF DIES 



part is blanked, edge n is subjected to a shaving action, owing 
to the thin strip of metal at this point. The amount of metal 
left for shaving should be equal to about 10 per cent of the 
stock thickness for mild steel. Dies designed on this principle 
are described in Chapter II. 

Burnishing Dies. — When an exceptionally good finish or 
polish is required, blanks which have been trimmed in a shaving 
die are pushed through what is known as a burnishing die. 
Such a die has an opening which tapers slightly inward toward 
the bottom, and it is finished very smooth, so that, when the 
blank is forced through by the punch, the metal around the 





DRAWN CUP 



Machinery 



Fig. 6. Simple Type of Drawing Die 

edges is compressed and polished. Naturally, the degree of 
finish on the blanks will depend largely upon the finish of the 
burnishing surface of the die. 

Embossing Dies. — An embossing die is used to form raised 
letters or an ornamental design, in relief, upon the surface of 
the work. An embossing die differs from a forming die in that 
the projections or designs made by it are comparatively small 
or shallow, and usually in the nature of relief work upon a surface, 
whereas a forming die gives the required shape to the work. The 
formation of lettered inscriptions, symbols, and decorative de- 
signs on all kinds of sheet-metal boxes and cans is done by em- 
bossing dies. A simple form of embossing die is one used for 
producing the circular ridges on the heads of tin cans, etc. 
Such a die would have one or more annular grooves and the 
punch would have annular ridges of corresponding size for 



DRAWING DIES II 

forcing the metal into the die grooves. Embossing is com- 
monly done in a die designed to cut, draw, and emboss the blank 
in one operation. An embossing die of this kind may be either 
a combination, a double-action, or a triple-action type, de- 
pending upon the nature of the work and the kind of press 
available. 

Drawing Dies. — Dies of this class are used for drawing parts 
from flat stock into cylindrical and various other shapes. There 
are several different classes of drawing dies, including plain 
drawing dies, combination dies, double-action dies, and triple- 
action dies. A very simple design of plain drawing die is shown 
in Fig. 6. The blank to be drawn is first cut in an ordinary 
blanking die; it is then laid in the drawing die, being located 
centrally with the die opening by an annular recess in the die 
face. After the clutch of the press is engaged, the punch de- 
scends and forces the flat blank through the die opening (as in- 
dicated by the right-hand view), thus forming it into a cup or 
shell of cylindrical shape. As the punch ascends, the drawn 
part is stripped from its end. This stripping may be caused 
by the contact of the upper edge of the cup with the lower edge 
of the die; some dies are also equipped with pivoted dogs or 
fingers which tilt downward as the punch descends and then 
swing in above the edge of the cup, thus stripping it off of the 
ascending punch. This form of die (commonly known as a 
" push- through die") is inexpensive as compared with some other 
designs and is often used for drawing operations, especially 
when the stock or metal is quite thick. Such dies are not 
adapted to drawing stock thinner than, say, -£% or -^ inch. 

Most first-operation dies, or those for drawing parts from flat 
blanks, are equipped with a blank-holder which presses against 
the outer part of the blank while the punch forces it through the 
die opening. The advantage of using a blank-holder is that 
when the blank is being drawn radially inward, if it is confined 
between the top surface of the die in a blank-holder or "pres- 
sure pad," wrinkles cannot readily form. 

The method of confining the blank and drawing it, or, in 
other words, the design of the die, depends upon the conditions, 



12 



CLASSES OF DIES 



such as the number of parts to be drawn, the amount or depth 
of the draw, type of drawing press available, etc. A simple and 
inexpensive form of drawing die of the type having a blank- 
holder is shown in Fig. 7. This die also draws a blank which 
has been cut out in another die. The blank to be drawn is 
placed in a recess in the die face, and when the press ram de- 
scends (after the clutch has been tripped by the operator) the 
blank-holder D first engages the blank; then, as the downward 
movement continues, the rubber pressure-pad F is compressed 
so that the blank is held firmly by the blank-holder while the 




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Machinery 



Fig. 7. Plain Drawing Die equipped with Blank-holder 

drawing punch E forces it through the cylindrical opening in 
the die. In this way, a cylindrical cup is formed from the flat 
blank, as indicated at A, B, and C, which show the blank, the 
half-drawn cup, and the finished cup. The cup is stripped from 
the ascending drawing punch by coming into contact with the 
lower edge G of the die opening. If a smaller and deeper cup 
is required, additional drawing operations in separate redraw- 
ing dies are necessary. Some dies of the type shown in Fig. 7, 
instead of having a rubber buffer, are equipped with a strong 
spring for operating the blank-holder; rubber, however, is 
preferable. 



DRAWING DIES 



J 3 



Combination Drawing Dies. — The combination type of die 
is one in which a blanking die and either a drawing or forming 
die are combined so that the blank is cut out and drawn or 
formed to shape in one stroke of the press. Owing to the con- 
struction, a combination die can be used in a single-action press, 
or one having a single slide. A typical combination die of the 
blanking and drawing type is illustrated in Fig. 8. Its oper- 
ation is as follows: When punch F descends and enters die E, 




Machinery 



Fig. 8. Combination Drawing Die for Use in Single-action Press 

it cuts out the blank and forces the blank-holder G downward 
against the tension of the rubber pressure attachment H, the 
blank-holder being supported upon the connecting pins /. As 
the downward movement continues, the blank is drawn to a 
cylindrical shape between the bore of the blanking punch F 
and the drawing punch D. 

When the ram of the press ascends, the shell is stripped from 
punch D by the blank-holder G; the shell is also ejected from 



14 CLASSES OF DIES 

the blanking-punch F by the "knockout" A'. The stem of this 
knockout extends up through the punch and has either a cross- 
pin or nuts at its upper end to hold it in place. The usual 
method of operating the knockout is to force it down posi- 
tively. This may be done by means of a stationary arm or bar 
which extends through an elongated slot in the slide. When 
the punch ascends the upper end of the knockout stem strikes 
this stationary arm and in this way the knockout is forced down, 
thus ejecting the drawn cup from the inside of the punch. An- 
other arrangement is as follows: A bar of rectangular section 
extends laterally through an elongated slot in the slide and en- 
gages the top of the knockout stem. When the punch ascends, 
the outer ends of this cross-bar strike set-screws so that the 
knockout is forced down. These set-screws are adjusted ac- 
cording to the stroke of the press. A rubber pressure attach- 
ment is generally applied to dies of this type instead of a spring, 
because the rubber is more durable and gives a more uniform 
pressure. 

In most cases, articles made in combination dies are in the 
form of shallow cups, etc., such as can tops and bottoms, pail 
bottoms and a variety of similar parts which frequently are not 
over j inch in depth. Dies of this class are also used for deeper 
articles, such as boxes and covers for blacking, salve, tobacco, 
etc., with depths up to about one inch. Most combination dies 
are so arranged that the finished article is automatically pushed 
out from the dies by the action of a stripper, as previously 
described; with a press set on an incline, the finished work will, 
therefore, slide back by gravity. 

Combination dies that are to be used for blanking and form- 
ing parts of either conical or irregular shapes are frequently 
made on the same principle as the one just described. Punch 
D, however, is shaped to conform to the shape to which the cup 
is to be drawn and on the under side of knockout A' there is a 
cavity or pocket which fits over the punch and forms a seat 
into which the work is forced. When the die is in use, the blank, 
after being cut, is drawn and formed between the face of knock- 
out A and the punch. If the part is not too deep, it can be 



DRAWING DIES 



IS 



blanked and drawn in one operation in a die designed in this 
way. 

Double-action Dies. — These dies are known as a double- 
action type because the blanking and drawing punches have in- 
dependent movements which are derived from the two slides of 
a double-action press; hence, the name of the die, in this case, 
indicates the type of press in which it is used. A double-action 
die of the "push-through" type is illustrated at A in Fig. 9. 
The combined blanking punch and blank-holder c is operated 
by the outer slide of the double-action press and moves slightly 
in advance of the drawing punch d, which is actuated by the 
inner slide. The outer slide is so arranged that, after making its 
stroke, it stops during about one-quarter of a revolution of the 




Fig. 9. Double-action Drawing Dies of " Push-through " and " Solid- 
bottom " Types 

crankshaft. The blank, after having been sheared from the sheet 
by the outer edge of punch c, is held between the end of punch 
c and the seat in the die, during the dwell of the outer slide. 
While the blank is thus held under a pressure which can be 
regulated to suit the special requirements of each case, the 
drawing punch d continues its downward movement, thus 
drawing the metal from between c and the die, into the form of 
a cylindrical cup. The drawing punch is so timed or adjusted 
that it will not reach the blank until the latter is subjected to 
sufficient pressure by the blank-holder for the drawing operation. 
While this type of die requires a double-action press, it is 
very much simpler in construction than the combination die 
illustrated in Fig. 8, which, as previously mentioned, is used in 



i6 



CLASSES OF DIES 



a press of the single-action type. The design of die shown at 
A, Fig. 9, is suitable for cylindrical articles which can be pushed 
through the die; hence, it is sometimes called a "push- through" 
cutting and drawing die, to distinguish it from the solid bottom 
type shown at B, which may be used for producing a cup of the 
shape illustrated. As will be seen, both the drawing punch and 
die conform to the shape of the part to be drawn. This type 
of die is equipped with knockout or "push-out plate" e at the 
bottom of the die, which rises on the upstroke of the press and 
lifts the drawn part from its seat in the die. This push-out 
plate, which is also called a "knockout," may be either spring 



« 





^i 



m 



E 

m 



M^^^^^^ 



■ 



JXD 



Machinery 



Fig. 10. Triple-action Die for Blanking, Drawing, and Embossing 

actuated or positively operated from beneath (as in the case of 
the die illustrated) by connection with the press. 

Triple-action Die. — A triple-action die, as the name implies, 
is one having three independent movements. This class of dies 
is used to produce articles requiring three operations, such as 
cutting or blanking, drawing, and stamping or embossing. 
They are frequently used in preference to a solid bottom, double- 
action die of the type shown at B, Fig. 8, because they deliver 
the finished part below the drawing die instead of pushing it up, 
thus enabling the operator to feed continuously and without 
waiting for each piece to be ejected before blanking for another 



DRAWING DIES 



17 



operation. A triple-action die is illustrated in Fig. 10. The 
cutting and drawing die A is mounted on a raised bolster B; C 
is the blank-holder and cutting punch; D, the drawing and em- 
bossing punch; and E, the embossing die. 

In the operation of this die, the blank is cut by punch C, which 
acts as a blank-holder, while the cup is drawn by punch D. As 
the drawing punch continues to descend, it carries the drawn 
cup downward until its lower surface engages the embossing 
die E. The latter is mounted on plunger F, and on its up- 
stroke imparts to the work the required impression, which may 
be a fancy design, lettering, etc. On the up-stroke of the punch, 



AIR VENT— r_ 




Machinery 



Fig. 11. (A) Plain Redrawing Die. (B) Redrawing Die with Inside 
Blank-holder 

the finished article is stripped by edge G, and, if the press is set 
on an incline, the work slides back by gravity beneath the raised 
bolster B into a box. With a die of this type, drawn and em- 
bossed articles can be produced as rapidly as plain covers in 
" push- through" dies. Triple-action dies are especially adapted 
for such work as drawing and embossing lettered covers for 
blacking boxes, baking powder cans, covers for lard pails and 
also for articles such as seamless sardine boxes, etc. 

Redrawing Dies. — After cups have been drawn in either a 
plain or double-acting drawing die, what are known as re- 
drawing dies are often used to reduce the diameters of these 
comparatively shallow cups and at the same time increase the 
depth or length, thus forming a shell. Some redrawing dies do 
not differ essentially from an ordinary plain drawing die, as will 



1 8 CLASSES OF DIES 

be seen by referring to sketch A, Fig. u. In this particular 
design, the cup is located in the die by an annular recess above 
the drawing surface and it is reduced in diameter and length- 
ened by simply being pushed through the die. There is, of 
course, a limit to the amount of reduction which can be ob- 
tained in a single drawing operation, and when a long shell is 
required, a series of redrawing dies are necessary, the steps or 
reductions in diameter being varied according to the thickness 
and quality of the metal being drawn. This subject is treated 
more fully in Chapter III. 

Sketch B, Fig. n, shows another type of redrawing die, which 
is especially adapted for drawing large, cylindrical parts when 
considerable reduction is required and when the stock is thin 
and liable to wrinkle. In this case, the cup to be redrawn is 
held by an inside blank-holder C as it passes between the lower 
beveled edge of the holder and the die, as the drawing punch 
descends. A double-action press must be used for a die of this 
kind, one slide operating the blank-holder and the other the 
drawing punch. The blank-holder presses against the cup and 
prevents the formation of wrinkles while the punch draws it 
into a deeper shape of less diameter. These dies, especially 
when used for large work, are frequently made of cast iron, 
treated in such a manner as to give a very dense and uniform 
texture to the metal at the working surfaces. Sometimes a steel 
ring is set into a cast-iron holder to form the drawing part of 
the die, and the blank-holder is made of a steel casting, which 
adds considerable to the durability of the tools. For articles 
which have to be very accurate in diameter, a hard steel sizing 
punch and die are sometimes used after the last redrawing 
operation. 

Forming Dies. — Forming dies are a type in which a blank 
is formed into a hollow shape by simply being pushed into a 
cavity of the required shape in the die, or a previously drawn 
cup is given a different shape by compressing it between a punch 
and die which conform to the shape desired. Drawing dies are 
also used for the formation of cup-shaped articles, but the 
drawing process differs from forming in that the stock is usually 



BENDING DIES 



19 



confined between two surfaces so that when drawn radially in- 
ward from between them, no wrinkles can form. To define the 
difference between the two types in another way, forming dies 
shape the metal by compressing and bending it, whereas, draw- 
ing dies so act upon a flat blank or a previously drawn cup, that 
the shape is changed by drawing the metal as the punch moves 
relative to the die or vice versa. 

Bending Dies. — Dies of this class are designed for bending 
sheet metal or wire parts into various shapes which are usually 
irregular and are produced either by pushing the stock into 
cavities or depressions of corresponding shape in the die or by 




Machinery 



Fig. 12. Bending Die 

the action of auxiliary attachments such as slides, etc., which 
are operated as the punch descends. A simple form of bending 
die would be one having an upper part or punch shaped to cor- 
respond with a depression in the die face; such a bending die is 
sometimes employed for bending flat, sheet-metal plates into an 
irregular shape. When the material to be bent is elastic or 
springy, the die must be made to allow for this, or so that the 
part is bent slightly beyond the required shape or angle to com- 
pensate for the backward spring when the pressure is released. 
Determining this allowance is, of course, a matter of experiment. 
An interesting design of bending die is shown in Fig. 12. As 



20 



CLASSES OF DIES 



will be seen, a swinging arm is pivoted at one end of the punch ; ' 
this arm carries a steel roller B. When the punch descends, this 
roller bends the stock down into the die at C. When the down- 
ward travel of the roller is checked by the die, the arm A swings 
to the left and continues to move in this direction until the 
roller has formed the work into the die, as shown by the lower 
finished part. The left-hand end of the work is formed between 
the die and the extension E of the punch. Before the punch has 
reached the end of its downward travel, the gripper F engages 
the work and holds it in position through the tension of the two 
springs shown in the illustration. This prevents any move- 




Fig. 13. Die for Curling Edges of Cylindrical Parts 

ment of the blank during the final stages of the bending operation. 
Curling Dies. — The dies used to form circular beads around 
the edge of drawn cylindrical parts, and for such work as form- 
ing cylindrical tubes or other shapes from flat stock, are com- 
monly known as curling dies. A curling die for beading the 
upper edge of a drawn cup is shown in Fig. 13. The curling 
punch has a central projection which fits into the work, and it 
is provided with a semi-circular groove which engages the edge 
of the cup as the punch descends. This causes the edge to curl 
over as indicated by the detailed sectional views, A, B, and C. 
The curling process is usually applied to thin metals less than 



THE SUB-PRESS 21 

3V inch thick, such as sheet tin, sheet iron, and sometimes brass 
or copper. Some curling dies are equipped with an ejector or 
"knockout" E, especially if the work is of such a shape that it 
cannot readily be removed by hand. 

The diameter of the bead that can be formed in a curling die 
must not be too large in proportion to the diameter of the work, 
and is ordinarily not over ^ s inch for tin plate and sheet iron. 
This limitation as to diameter is due to the fact that, as the 
edge is forced outward by the curling punch, the circumference 
increases and the metal is stretched; hence, if the diameter of 
the bead is too large, this excessive stretching of the material 
causes it to crack in a radial direction at numerous points around 
the edge. If the metal is well annealed, naturally a com- 
paratively large bead can be formed. Curling dies, especially 
when used for forming a bead or curl around a wire at the edge 
of tin- ware, etc., are commonly referred to as wiring dies. Some 
wiring dies are practically the same as the one just described, 
excepting that the die has a floating spring-supported ring upon 
which the wire ring rests. As the punch descends, the curl is 
formed around the wire, enclosing it. Curling or wiring dies for 
tapering parts such as milk pans, etc., have a curling punch 
which is composed of six or eight segments instead of being 
solid, so that it can contract when entering the tapered part. 

The Sub-press. — A sub-press cannot be defined as a special 
class of die, but merely as a principle on which different kinds 
of dies may be worked. The sub-press principle is simply that 
the upper and lower portions of the die are combined into one 
self-contained unit so arranged as to always hold the upper and 
lower members in exact alignment with each other. A com- 
mon form of sub-press construction is shown in Fig. 14. It con- 
sists of a base B which is clamped to the press, a frame or 
"barrel" A fitted to the base, and a plunger C which slides 
vertically in an adjustable babbitt bearing. The plunger head 
or "button" D is connected to the press slide by what is known 
as a "hook." The latter is merely a slotted member which 
engages the annular groove seen at the upper end of the plunger. 

The compound type of die is commonly used in a sub-press. 



22 



CLASSES OF DIES 



The upper die is located in the plunger and the lower die in the 
base. This sub-press construction permits of a high degree of 
accuracy as it insures an accurate alignment of the various 
members of the die. Sub-presses are largely used for producing 
such parts as small wheels and gears and other delicate parts 
for clocks, watches, meters, time recorders, and other similar 
pieces which must be made with great accuracy and uniformity. 
Although, in some cases, one sub-press can be made to take 



1 D 




Machinery 



Fig. 14. 



Sub-press for Aligning and Guiding Upper and Lower Members 
of Compound Dies 



several sets of punches and dies, it is customary, and generally 
advisable, to have a separate sub-press for each set, as one of 
the advantages gained in using the sub-press is in being able to 
quickly change from one die to another; when separate sub- 
presses are used this can be done by simply loosening the clamps, 
changing the presses and re-clamping. In addition to this ad- 
vantage, there is no time wasted in aligning the punches and 



THE SUB-PRESS 



23 



dies; moreover, the danger of shearing the punch or die, as a 
result of careless alignment, is entirely eliminated. 

Another advantage of the sub-press, dependent in part on the 
accuracy of alignment provided, and the corresponding accuracy 
in fitting which can be given to the cutting edges, is that the 
work is remarkably free from fins and burrs. A consideration 
of the action of the press will show that there is practically no 
chance for burrs to form in a piece even where they would in an 
ordinary blanking die. It is, of course, necessary for the die to 
descend until the punch has all but entered it, if clean work is 
to be produced. There is a slight difference in the practice of 




Fig. 15. Swaging and Blanking Die 

different operators in this respect, although this difference in 
practice would be expressed in the dimensions of only 0.002 or 
0.003 inch, perhaps. Some of them adjust the stroke so that 
the die does not quite meet the punch. Others prefer to have 
them meet and even enter by very slight amount. The only 
objection to the use of sub-presses is the extra cost, and this is 
often more apparent than real. The difference in cost is more 
noticeable in a simple, low-priced die than in a compound die, 
and, in fact, in the latter case it often occurs that a complicated 
die can be made with less expense by using a sub-press than by 
any other method. 

Some dies which operate on the sub-press principle differ from 
the construction shown in Fig. 14, in that the upper and lower 



24 CLASSES OF DIES 

die members are held in alignment by guide-rods which are 
fastened to the lower die and extend through holes in the upper 
die. This construction is common for large dies, the usual 
method being to have four of these guide-rods, one at each 
corner of the die. Dies of this kind are sometimes called "pillar 
dies." 

Swaging Dies. — Swaging dies are a type in which parts are 
formed to the required shape by compressing the metal so that 
the impressions in the punch and die faces are reproduced upon 
the work; in other words, instead of shaping the metal by 
cutting, bending, or drawing, it is formed by compression. 
The pressure required for swaging is relatively high because it 
must be sufficient to cause the metal to flow into the punch and 
die cavities or depressions. A combined swaging and blanking 
die of simple form is shown in Fig. 15, which is used for making 
the small part illustrated at A. These parts are formed by 
feeding an annealed brass wire through the die, swaging to the 
required form, and then blanking it. At B is shown the end of 
the wire after the swaging and blanking punches have done their 
work. The swaging punch is illustrated at C, while D is the 
punch which cuts and forces the blank through the die. The 
wire is fed through a hole in guide E which keeps it in proper 
alignment with the working faces of both die and punch. The 
dotted lines shown on the swaged end at B indicate where the 
next piece A will be cut from the stock by the blanking punch 
D. A stripper (not shown) removes the scrap from the blanking 
punch. The pieces after coming from the die are tumbled to 
remove all fins, and then drilled. 



CHAPTER II 

DIEMAKING METHODS AND BLANKING DIE 
CONSTRUCTION 

When constructing a die, the degree of accuracy with which 
it is made and the general finish will depend somewhat upon 
the amount of work that it will be required to do or the number 
of pieces to be produced. When this number is comparatively 
small, the most inexpensive die that will do the work properly 
should be made. Dies of this class are known as "emergency 
dies," as they are quickly made and are not constructed to 
withstand long and continuous usage. When, however, a die is 
to be used incessantly for a long period, or, perhaps, until it is 
worn out through use, the materials used and the quality of the 
workmanship should be of the highest possible grade and every 
detail brought as near perfection as possible. Of the many 
different kinds of dies in use, the blanking die is the most com- 
mon type. The reason for this is that almost all work that re- 
quires the use of various other kinds of dies either has its begin- 
ning with the blanking die, or is cut from the flat stock after it 
is completed by other dies which may or may not be combined 
with the blanking die. In making a blanking die, there are a 
few essential points to be taken into consideration, among which 
are the following: 

i. Use good tool steel of a sufficient length, width, and thick- 
ness to enable the die to withstand the work for which it is 
intended. 

2. In laying out the die, care should be taken that as little of 
the stock as possible is left over, as waste, in cutting out the 
blanks. 

3. Be sure not only that the die has the proper amount of 
clearance but also that the clearance is filed or machined straight, 
so as to enable the blanks to drop through readily. 

25 



26 i BLANKING DIE CONSTRUCTION 

4. In working out the die, machine out as much as possible 
to avoid excessive filing. 

Kind of Steel Used for Die Work. — For most work the stock 
used in making punches and dies should be a good quality of 
tool steel. A die that has cost from ten to a hundred dollars 
for labor is as liable to crack when hardening as though the same 
steel had been made into any other form of tool; and in fact 
its shape and irregular thickness of stock at various points, 
together with numerous sharp corners that are liable to be 
present, make a tool that requires extreme care in handling when 
hardening. A good grade of tool steel, free from harmful im- 
purities, is less liable to crack than an inferior grade, and the 
slight difference in cost is offset many times by the cost of labor 
in the die construction. This does not necessarily mean that a 
high-priced steel must be used for this class of work; simply a 
good quality of steel, low in percentage of those impurities which 
cause trouble when the steel is hardened. When we speak of 
good, reliable steel, we do not necessarily mean high-priced steel. 

In all shop operations true economy should always be practiced, 
and many times this may be done by a saving of tool steel. 
In the construction of some dies a saving may be effected by 
making the body of cast iron and inserting bushings of tool 
steel; then if at any time the dies become worn they can be re- 
placed by simply making new bushings, and if ordinary care is 
taken, the holes will be concentric and consequently the proper 
distance apart, so there will be no necessity of altering the 
location of the punches, as might be the case if a die made of a 
solid piece was hardened. 

Some diemakers, when making irregular-shaped punches that 
are to cut thin stock, make them of machine steel and case- 
harden them. Soft steel, casehardened, does not change its 
form as much as tool steel, and even if the punch does change 
a trifle, the interior is soft and can be readily forced back to 
position. The outside being hard, the punch will wear nearly 
as long as one made from tool steel, for practically the only wear 
on a punch is when passing through the stock. For thin brass 
the punch works well when made of tool steel and left soft, and 



LAYING OUT DIES 27 

when worn badly the punch can be peened on the face enough 
to upset it and then be sheared into the die. 

Value of Annealing. — Many diemakers overlook the im- 
portance of first roughing a die nearly to size and then carefully 
annealing it. There are internal strains set up in the bar of 
steel during its manufacture which are sure to cause distortion 
of the die or tool unless these strains are removed before the 
work is brought to its finished size. Some steel may be free 
from strains, but there is no way of determining beforehand 
whether the steel has "settled" or not; therefore, to guard 
against distortion, the careful diemaker will not take chances, 
but will anneal the piece after it has been roughed out, because 
annealing relieves these internal strains. 

The following test illustrates the value of annealing before 
finishing: Four pieces of tool steel were cut from the same bar 
and the same amount of stock was removed from each piece, 
finishing them all over to exactly the same dimensions. They 
were then marked A , B, C, and D. Pieces A and B were annealed 
after roughing, but pieces C and D were machined to size. The 
pyrometer was used to insure heating all the pieces to the same 
temperature of 1400 degrees F. The bath was clean water 
with a temperature of 68 degrees F. The pieces were heated 
separately in a muffle furnace and were allowed to remain in 
the bath exactly one minute, in each case. The result of this 
comparative test was as follows: The pieces A and B were 
slightly distorted, but the pieces C and D were distorted to such 
an extent that they were useless. 

Laying Out Blanking Dies. — A most important point for the 
diemaker to bear in mind in making blanking dies for odd shapes 
is to lay them out so that the minimum amount of metal will 
be converted into scrap. In fact, hardly too much stress can 
be laid upon this one point alone, as it is an easy matter to waste 
a considerable percentage of the stock by lay-outs which may 
appear to be fairly economical. In the following, the object will 
be to point out by actual examples how stock can be saved which 
may be converted into scrap, if the diemaker is not constantly 
watching out for possible economies. 



28 



BLANKING DIE CONSTRUCTION 



Beginning with a simple illustration, it sometimes happens 
that by laying out the dies so that the blanks are cut from the 
strip at an angle instead of at right angles to the edge of the 
stock, a considerable economy of metal can be effected. As 
will be seen by referring to Fig. i, the angular location permits 
the use of narrower stock and materially reduces the amount of 
scrap metal. By comparing the upper and lower views, the 
saving in metal by diagonal blanking is apparent, as it is not 
only possible to use a much narrower strip of stock, but more 




Fig. i. Illustration of the Saving of Metal effected by Cutting the Blanks 
Diagonally from the Stock 

blanks can also be obtained from a given length, as will be 
understood by noting the difference between the dimensions a 
and b. When thousands of blanks are to be produced, the sav- 
ing in metal that is effected is considerable. The most eco- 
nomical lay-out can often be determined easily and quickly by 
cutting out a few paper templets and arranging them in various 
ways until the best method of blanking is ascertained. 

When the shape of the blanks is such that there would, un- 
avoidably, be a considerable amount of metal between the 
punched holes, the stock can, at times, be cut to a better ad- 



LAYING OUT DIES 



2 9 



vantage by so locating the stop- or gage-pin that sufficient 
metal is left between the holes to permit the strip being turned 
around and again passed through the press. If a large number 
of blanks are to be made, however, a double blanking die would 
be preferable. 

An example of stock which is passed through the die twice is 
shown in Fig. 2. The upper view shows the stock after the 





Machinery 



Fig. 2. (Upper View) Stock that is passed Once through Blanking and Piercing 
Die. (Lower View) Stock after the Second Passage through the Die 

first passage and the lower view the scrap after the second pas- 
sage. The lay-out of the blanking die for this operation is 
shown in Fig. 3. Each blank is pierced with three small holes 
as the plan view of the die indicates. Besides cutting and 
piercing the blank when the stock is run through the first time, 
the three small holes for the blanks to be cut out during the 



3° 



BLANKING DIE CONSTRUCTION 



second passage are also pierced, as the upper view, Fig. 2, shows. 
This is done for the reason that when the metal is run through 
the second time, the pierced holes serve as a guide in locating 
the stock and prevent the cutting of "half blanks" by "running 
in," or, in other words, the liability of cutting imperfect blanks 
by punching into that part of the metal from which blanks have 
already been cut. This guiding action is effected by three pilot 
pins in the blanking punch which engage the three pieced holes 



K — 1- 

A 



"7? K-~|f- H<:414%j 





Machinery 



Fig. 3. Lay-out of Die for Blanking and Piercing Stock as Illustrated 

in Fig. 2 

made when the strip was run through the first time. The pilot 
pins engaging with the pierced holes cause the second lot of 
blanks to be cut centrally with the holes, and also to be ac- 
curately centered between the portions of stock from which the 
blanks have already been cut. When this die is in use, the metal 
is run through in the usual way from right to left until half of 
the required amount of blanks is cut, after which the piercing 
punches for the holes are taken out and the metal is run through 
again and the other half of the required amount of blanks is cut. 
In laying out this die, which is done after the manner shown in 
Fig. 3, the line A- A is used as the center-line for the upper 



LAYIXG OUT DIES 



31 



piercing holes and the line B-B as the center-line of the blanking 
part of the die. The line C-C is the center-line that marks the 
center of the next blank to be cut and is laid out § f inch from 
the line B-B. This dimension is hxed by the fact that the 
widest part of the blank is f § inch, and the bridge between the 
blanks is $\ inch, the sum of which equals the distance from 
center to center of adjacent blanks. The line D-D is the center- 
line for the blank which is cut when the metal is run through the 
second time, and is made at 0.414 inch or one-half of ff from 










r\ °r 


7 


w 


/ ° 


' 


)°J 


U \J 





THE BLANK 












Machinery 



Fig. 4. Double Blanking and Piercing Die — Appearance of Stock that is 
passed through the Die 

the line C-C, inasmuch as the blanks cut at the second passage 
of the stock are midway between those cut the rirst time the 
stock goes through the die. 

At .4 in Fig. 4 is shown a double die for blanking and piercing 
brass stock, producing the shape shown in the sketch at the 
left; it is laid out so as to save as much of the metal as is practi- 
cally possible without added expense so far as the operation of 
blanking and piercing is concerned. By referring to sketches 
B and C, it can be seen that the strip of metal from which the 
blanks are cut is run throusrh a second time for reasons that will 



32 



BLANKING DIE CONSTRUCTION 



be given. One reason is that wider metal can be used by doing 
this, which in itself is a saving so far as the cost of metal is con- 
cerned. Wide brass can be bought at a lower price per pound 
than narrow brass. The other reason is that a strip of metal ^V 
inch wide and as long as the entire length of the strip is saved 
on every strip that is run through. If narrow metal were used, 
there would be waste of f inch of metal (i.e., -^ inch on each 
side) of every strip run through, and on two strips from which 




Q fiEEB90 ! S 



FOURTH STROKE 



Machinery 



Fig. 5- 



Diagrams Illustrating Progressive Action of Double Die shown 
in Fig. 4 



no more blanks could be cut than from the wider strip shown at 
C, there would be waste of \ inch of metal. On the other hand, 
by using wide metal and running it through the die twice, the 
waste would be only T 3 g inch, as indicated at C. 

To fully understand the manner in which the metal is gradually 
worked up after each stroke of the press, short sections are shown 
in Fig. 5. At the first stroke four holes are pierced and two 



LAYING OUT DIES 



33 



plain blanks A, having no holes, are cut out. At the second 
stroke there are also four holes pierced and the two blanks B, 
for which the holes were pierced at the previous stroke, are 
cut. At the third and fourth strokes the holes begin to match 
in with each other, as shown, so that when the metal is run 
through it will look like the strip shown at B, Fig. 4. It should 
be borne in mind that four holes are pierced and two blanks are 
cut at each stroke of the press; also that the metal is fed after 



13" 



/cMflrfi 




STOCK THAT HAS PASSED 
THROUGH DIE 



Machinery 



Fig. 6. Die for Piercing and Blanking Two Washers Simultaneously 

each stroke a distance x equal to the distance from the center of 
the leading blanking punch to the center of the first set of pierc- 
ing punches, as indicated in the strip marked "first stroke." In 
this particular case the feeding movement x equals ff inch, 
and the die is so laid out that the distance y equals one-half the 
feeding movement or f-f inch. 

Laying Out Dies for Washers. — To lay out a single washer 
die is a very easy matter, but to lay out a die for cutting two or 



34 



BLANKING DIE CONSTRUCTION 



more washers at one time, so as to cut the greatest amount of 
blanks from the least amount of stock, is not understood as it 
should be. In laying out a washer die for blanking two or more 
washers at one time, one of the main points to be remembered 
is that all the holes from which the blanking and piercing are 
done must be laid out in an exact relation to each other, so as 
to eliminate the possibility of "running in," i.e., cutting im- 
perfect or half blanks by cutting into that part of the metal 
from which blanks have already been cut. The required amount 
of blanks must also be considered, for it sometimes happens that 




STOCK THAT HAS PASSED 
THROUGH DIE 



^ 




A 






<-B"-M 


fV 








k x 


1 


0-E"-> 


<-#•-> 











PLAN OF DIE 



Machinery 



Fig. 7. Die for Piercing and Blanking Three Washers Simultaneously 

the amount wanted does not warrant the making of a die that 
will cut more than one at a time. 

Fig. 6 shows how a die is laid out for blanking and piercing 
two washers at one time, so as to utilize as much of the metal 
as possible. As shown, the f-inch holes marked C and D are 
the blanking part of the die, while the f-inch holes A and B are 
for the piercing punches. The distance between the center of 
C and A is f| inch, as is also the distance between D and B. 
By referring to that part of the illustration which shows a sec- 
tion of the stock after it has been run through the die, it will be 
seen that there is a narrow margin of q\ inch of metal, known 
as "the bridge," between the holes. In laying out the die this 
margin must be taken into consideration, when determining the 



LAYING OUT DIES 35 

center-to-center distance; thus, diameter of washer to be cut 
plus bridge equals distance from center of piercing punch to 
center of blanking punch. For example, f + g\ = ||. The 
dotted circle on the plan view of the die shows that the die is 
laid out so that one washer is skipped in running the metal 
through at the start. The holes are located in this way in 
order to make the die a substantial and strong one. It can 
very readily be seen that if the circle E were the blanking part 
instead of D, the die would be a frail one, and would not be 
strong enough for the work for which it is intended. Another 
important point in laying out a die of this kind is to lay it out 
central, or so that when it is keyed in position ready for use in 
the center of the die-bed, it will not have to be shifted to the 
right or left side in order to make it line up with the punch. 
Incidentally, the punch plate, which holds the blanking and 
piercing punches in position, should also be laid out central. 

Fig. 7 shows the lay-out for blanking and piercing three washers 
at one time. A section of the stock after it has been run through 
this die is shown to the left in the illustration. As will be seen, 
the holes match in very close together and very little stock is 
left in the form of scrap; moreover, the holes are "staggered" 
instead of being in a straight line across the width of the sheet. 
This is done in order to save metal; the dotted circle F is merely 
drawn to show that wider metal would have to be used if the 
holes were in a straight line. 

The plan of a die for blanking and piercing eight washers at 
one time is shown to the right in Fig. 8. The holes which are 
numbered are for blanking and those which are lettered are for 
piercing the holes in the washers. This die is laid out similarly 
to the one shown in Fig. 7, with the exception that there is pro- 
vision for eight blanks instead of for three. A section of stock 
after it has been run through this die is shown to the left. To 
give a better idea as to how the blanks are punched out in the 
manner shown, the sixteen holes in the metal from which blanks 
have been cut are numbered and lettered the same as the die. 
The metal is fed through in the usual way, which is from right 
to left, and the holes are, of course, pierced before the blanks 



36 



BLANKING DIE CONSTRUCTION 



are cut. By referring again to Fig. 8, the lay-out for cutting two, 
three, four, five, six and seven blanks can be determined. The 
parts numbered and lettered i-A and 5-E are the lay-out for 
two blanks; for three blanks, i-A, 2-B, and 5-E; for four 
blanks, i-A, 2-B, 5-E, and 6-F; for five blanks, i-A, 2-B, 
y-C, 5-E, and 6-F; for six blanks, i-A, 2-B, $-C, 5-E, 6-F, 
and 7-G; for seven blanks, i-A, 2-B, 3-C, 4-D, 5-E, 6-F, and 
7-G. It should be remembered that all holes in dies of this 
kind are lapped or ground to size after hardening; they should 



poooo 

J00OCX 
UD00Q 



STOCK THAT HAS PASSED 
THROUGH DIE 



o© 



0© 



0© 



0© 



0© 



0® 



0® 



0© 



PLAN OF DIE 



Machinery 



Fig. 8. Die for Piercing and Blanking Eight Washers Simultaneously 

be perfectly round and have 1 degree clearance. In some shops 
the holes are left straight for f inch, and then tapered off 2 
degrees. 

Templets for Blanking Dies. — When making a blanking die 
it is common practice to begin by making a templet that con- 
forms to the shape of the blank which the die is to produce. 
This templet is then used as a gage when finishing the hole in 
the die. Sheet steel is commonly used for templets. The thick- 
ness depends somewhat upon the size of the templet, but for 
comparatively small work, steel about /o inch thick will suffice. 



LAYING OUT DIES 



37 



The outline of the templet should be laid out very carefully, 
and finished to conform exactly to the required shape and size 
of the hole to be cut in the die blank. It is absolutely neces- 
sary, if accurate work is to be produced by punches and dies, 
that the templet be accurate. This is one of the first points 
which the diemaker should be sure of before beginning to make 
the punch die. At times it requires a considerable degree of 
skill to make a templet that will answer for the work in hand. 

As an example, the templet shown at A in Fig. 9 may be re- 
ferred to. After blanking and bending the small projection at 
the top of the piece to be made, it was to be closed around a 









-p 

fix 




O) 




A 


» 




n ! 




0)1 

c 


1 

1 1 


B 


c 




Machinery 



Fig. 9. Examples of Blanking Die Templets 

groove in the end of the rod, as shown at B. After closing, the 
outside of the blank was supposed to be circular. The die was 
made to a templet and it was found less difficult to make the die 
than the templet. In this instance, it was necessary to make 
two pieces of the desired shape exactly alike, one of which was 
closed on the grooved rod and tested. The points that were 
not right were located on the one that had not been closed up. 
Then others were laid out from it, due allowance being made for 
the imperfections of the first. When making the templet, two 
pieces of stock were placed together, and one half was worked 
to the laying out lines, as shown at C. After the other half had 
been blocked out somewhere near the line, the pieces were 
reversed and each half that had been blocked out was, filed to 
conform to the finished half. In this way the ends were made 



38 



BLANKING DIE CONSTRUCTION 



duplicates. When one templet was forced down or closed on 
the rod and was found correct, the other answered for the temp- 
let to be used in laying out the die, and as a gage when finishing 
the hole in the die. 

In order that templets may be easily handled, it is customary 
to attach some form of handle to them, which is sometimes done 
by drilling and tapping a hole in the templet, and cutting a 
short thread on a piece of wire which is screwed into the tapped 
hole. Another common method is to attach a piece of wire by 
means of a drop of solder, as shown at D. 

Laying Out Die from Templet. — The templet or master blank 
for a blanking die may be used for laying out the die by trans- 





D >Z^ 

■ 'iiii'iDJiiiiiim ; 



G 
717TITT1T 1 





SECTION a;-* 

Machinery 



Fig. 10. Diemakers' Crab Clamp 

ferring the outline of the templet directly to the die-face. The 
top surface of the die blank should be brightened with a piece 
of emery cloth, and the surface prepared for laying out by 
either applying a coppering solution or by heating the die blank 
evenly all over until a dark blue color is obtained, and then im- 
mersing it in oil. The surface will then be either coppered or 
blued, depending upon the method employed, and on such 
surfaces all lines made by a sharp scriber will be bright, and 
made plainly visible by the contrast with the darker back- 
ground. The templet, or master blank, can now be used for 
laying out the die. It is first clamped on the face of the die 
blank; then, by following the outline of the templet with a 



MACHINING DIES 39 

sharp scriber, its shape is transferred to the face of the blank. 
Before locating the templet, however, the most economical way 
of cutting the blanks from the stock must be determined; that 
is, the way to obtain the greatest number of blanks from a given 
weight of stock, as explained in connection with the laying out 
of blanking dies. 

A type of clamp which is very convenient for clamping the 
templet to the die-face, as well as for other die work, is shown in 
Fig. 10. With this clamp there is no time wasted in screwing 
the clamp screw C up and down when pieces of different thick- 
nesses are placed between the arms F, because the jaws A are 
made so that they can slide up and down on the arms F, which 
are provided with steps or notches so that the jaws can rest at 
various places on them as shown. The springs E act as frictions, 
and prevent the jaws from dropping when not resting on the 
steps. The arms F swing on pins G, thus making it possible to 
accommodate various widths of the die blanks. . 

Machining Opening in Blanking Die. — After the die has been 
laid out accurately the next step is to machine the hole for the 
blanking punch. The way in which this is done will, of course, 
depend somewhat upon the shape of the blank which is to be 
produced. As the hole through the die which we have selected 
as an example (which is shown in Fig. n) has circular ends, the 
lathe can be used to advantage for machining these ends. When 
dies have circular ends or arcs, the machining of the opening 
can also be facilitated by drilling, the sizes of the drills being 
selected with reference to the radii of the circular sections. 
For instance, if the core of the die illustrated in Fig. n were to 
be removed entirely by drilling, a large drill should be used for 
the circular ends and a smaller size for drilling the rows of holes 
about the central core. Of course, boring out the ends in the 
lathe would be a more accurate method than drilling. When 
drilling a row of holes for the purpose of removing a core (which 
is a very common method) if each alternate hole is first drilled, 
as indicated at A, and then the remaining ones, the holes can 
be spaced closer and drilled with less difficulty, and there will 
be no bridges between adjacent holes to hold the core in place. 



4Q 



BLANKING DIE CONSTRUCTION 



As a blanking die must have clearance, in order that the 
blanks, when sheared from the stock, may fall through the die, 
it is common practice, when drilling, to insert a thin strip be- 
neath the blank and on the side farthest from the hole being 
drilled, so that the hole is inclined from the vertical equal to the 
clearance angle. The holes can also be drilled at right angles 
to the face of the die and then be reamed out with a taper reamer, 
but the former method is more practicable.- 

After drilling, most of the surplus metal can be removed with 
a sharp chisel, but if the die is large it can be machined on the 




Fig. ii. Example Illustrating Method of Removing Core of Blanking Die 

planer or shaper by strapping it to an angle-plate which is in- 
clined to the vertical sufficiently to give the die the proper 
amount of clearance, or by clamping it between two i^ degree 
parallels. Of course, this work may be done more easily on a 
regular die-slotting machine or die shaper, if one is available. 
If chipping is resorted to, the chisel should always be driven 
away from the top of the die as there is danger, when chipping 
from the other direction, of the metal breaking away outside 
of the lines. At times it may be advantageous to drill a single 
hole large enough to insert a milling cutter, and then work out 
the core on a vertical milling machine, or a horizontal machine 
with a vertical attachment. A taper cutter can then be used 
for giving the die clearance. Regular die milling machines are 
also commonly used, and the slotting attachments for universal 
milling machines are also convenient for machining blanking dies. 



MACHINING DIES 



41 



Die Shaping and Slotting Machines. — A machine that is 
especially adapted for die work is shown in Fig. 12. This is a 
Pratt & Whitney vertical shaper, and the operation illustrated 
is that of machining the openings in a die for armature disks. 
The work-table of this shaper can be given a transverse, longi- 
tudinal, or rotary movement. The ram which carries the plan- 




Fig. 12. Machining Holes in Armature Disk Die in a Vertical Shaper 

ing or slotting tool moves vertically while the table is fed, either 
by hand or automatically, in whatever direction is required. 
The ram is mounted in an independent bearing, the upper part 
of which is pivoted on a trunnion that enables the bearing and 
ram to be set in an angular position which is indicated by de- 
gree graduations. This feature makes the machine very con- 



42 



BLANKING DIE CONSTRUCTION 



venient for machining openings in blanking dies, because the 
excess metal is readily removed and at the same time a uniform 
clearance angle is given to the cutting edge of the die. 

The tool is held in a slotted toolpost carried in a clapper 
which permits the tool to clear the work on the return stroke, 




Fig. 13. Universal Shaper Arranged for Slotting a Blanking Die 

the same as on a horizontal shaper. When exceptionally long 
tools are required on internal work, the clapper can be clamped 
rigidly to the head. The tool-head can be swiveled to four 
different positions so that the tool can be set for slotting different 
sides without changing the position of the table and by simply 



MACHINING DIES 43 

using the transverse or longitudinal feeding movement, thus 
insuring accuracy between the surfaces. 

The machine shown slotting out a blanking die in Fig. 13 is 
known as a universal shaper, although it is, in reality, a shaper, 
slotter, milling and drilling machine combined. This machine 
(built by the Cochrane-Bly Co.) is especially adapted for die 
work, and, owing to its universal features, drilling, milling, and 
shaping or slotting operations can be performed at one setting 
of the die. For instance, when making a blanking die, the open- 
ing can be machined by first drilling a hole to form a starting 
place for the slotting tool; the latter may then be used to re- 
move the core, after which the edges are slotted out to the re- 
quired form and clearance angle and close to the finished size, 
so that little filing is necessary. Power feed is provided for the 
longitudinal cross-movements of the table. The machine also 
has either a continuous or intermittent feed. When the milling 
spindle is being used, the feed is continuous, whereas an inter- 
mittent feed, which takes place. on the; return stroke, should be 
used when the shaper ram is in action. Tool-holders of various 
styles for holding slotting or shaping tools can be attached io 
the head. The ram is equipped with a mechanism which pro- 
vides a positive relief for the tool on the upward or retufn 
stroke. Both the shaper and the milling heads have an inde- 
pendent adjustment about an axis at right angles to the main 
head, which makes it possible to locate them at any angle. The 
auxiliary circular table shown in Fig. 13 may be rotated by 
hand or by means of a power feed. The periphery of the table 
is graduated in degrees and the dial enables it to be adjusted 
within 2\ minutes of a given angle. The handwheel shown in 
the illustration may be replaced by a dividing attachment hav- 
ing index plates and a sector, similar to the dividing head of a 
universal milling machine. This attachment is convenient when 
machining dies that require accurate spacing. 

The openings in blanking dies are often machined in slotters 
especially designed for work of this class. A die slotter which 
represents a typical design is equipped with a short-stroke ram 
which can be set at an angle with the work-table for machining 



44 



BLANKING DIE CONSTRUCTION 



the required amount of clearance. The table is circular and can 
be rotated for slotting circular openings. This circular table is 
mounted on compound slides which provide lateral and trans- 
verse feeding movements. The machine is of the column-and- 
knee construction, thus providing vertical adjustment for the 
work-table. 

Blanking dies are also slotted on an ordinary column-and- 
knee type milling machine, by using a slotting attachment. 
This attachment is bolted to the face of the column and is driven 




Thurston Die Milling Machine 



from the main spindle of the machine through suitable gearing, 
which transmits motion to the crank that operates the slotter 
ram. 

Undercutting Die Milling Machine. — A machine especially 
designed for die work is shown in Fig. 14. This machine is so 
arranged that the cutter is driven from beneath the work-table 
and extends up into the die opening instead of being held by a 
spindle from above. One advantage of this construction is that 
lines on the die-face showing the outline or contour of the die 
opening are not obstructed by the cutter or spindle. The die 



DIE FILING 45 

to be milled is held on a table which is carried by cross and 
longitudinal slides. By manipulating the handles which oper- 
ate the two slides, the work is fed against the milling cutter in 
the required direction. The cutter may be either straight or 
tapered to suit the amount of clearance required for the die 
opening. When using this machine, it is necessary to drill a 
hole through the die to form a starting place for the cutter which 
is then fed around the outline of the die opening, thus cutting 
out the entire core or center in the form of a solid block. The 
raising or lowering of the cutter-slide is effected by means of the 
lower handle seen at the front of the machine, whereas the 
upper handle and the one at the right end control the cross and 
longitudinal movements, respectively. There is a pointer on 
the machine which remains in a fixed position with reference to 
the cutter, so that when the latter is operating below the surface 
of the die the pointer indicates its position. The entire frame 
of the machine is mounted on trunnions, so that the work can be 
inclined to any desired position, in order to give the operator 
the best possible light on the surface being milled. 

Finishing a Blanking Die by Filing. — After the opening in a 
blanking die has been machined to approximately the required 
shape and size, the exact shape and size is ordinarily obtained 
by filing. This may be done by hand or in a filing machine. 
When the die is to be filed by hand it is fastened in a vise with 
its top or face toward the back of the vise. The hole is then 
filed until it fits the master blank or templet. The templet 
should be frequently tried in the hole, the bearing points being 
marked with a pencil, and then removed with the file; this 
operation is repeated until the hole fits the templet perfectly 
and is large enough to allow it to just pass through. When 
testing the hole, the surface of the templet should be kept 
parallel with the top of the die. As the work is nearing com- 
pletion, it may be necessary to remove it from the vise each 
time the templet is inserted, to enable one to see the minute 
openings. A piece of white paper held on the opposite side of 
the blank will, however, suffice for the earlier stages of the 
work. When fifing, it is sometimes advisable to protect ends 



46 



BLANKING DIE CONSTRUCTION 



which may have been finished previously by the method illus- 
trated in Fig. 15. Piece A prevents the edges of hole P in the 
die from coming into contact with the edge of the file when the 
die is filed out. Piece B simply serves the purpose of permitting 
the die to be held parallel in the vise. 

When finishing the hole in the die, the clearance should be 
filed as straight as possible, so that the blanks, when cut, can 
easily fall through the opening. To file a narrow surface straight 
is difficult and requires considerable practice, and while one 
becomes proficient in work of this kind only through practice, 




Blanking Die in Vise ready for Filing 



still a hint as to the proper method of procedure may be useful. 
When the file begins its stroke, the downward pressure exerted 
by the left-hand holding the outer end should be maximum, 
while a minimum pressure is given by the right-hand; as the 
rile advances, the pressure from the left-hand decreases, while 
that from the other increases. After considerable practice, one 
is enabled, unconsciously, to regulate the pressure on each end 
of the file so that any "rocking" motion of the file is prevented. 
If the surface being filed becomes rounded this can usually be 
remedied by using a sharp scraper which will cut the metal quite 
rapidly. In filing out the die, it is convenient to have a set of 



DIE FILING 



47 



small "squares" which vary from ninety degrees, an amount 
equal to the angle required on the die for clearance. These may 
be made from yg-inch sheet steel with the base | inch wide by 
2 inches long, and the beam | inch wide by \\ inch long, or they 
can be made to suit the requirements. It is generally found ad- 
visable to have these ranging from \ degree to 2 degrees, vary- 




Fig. 16. Cochrane-Bly Filing Machine at Work on a Blanking Die 

ing by \ degree. The number of degrees that these vary from 
90 should be marked on the different squares to designate them. 
Die Filing Machines. — Vertical filing machines are used by 
many diemakers for filing the openings in blanking dies. The 
use of a Cochrane-Bly filing machine is indicated in Fig. 16. 
The table of this machine is adjustable about two axes at right 
angles to each other so that it can be tilted for filing clearance 
in dies, as well as for other angular work. A screw feed, operated 



4 8 



BLANKING DIE CONSTRUCTION 



by hand, is provided for feeding the work against the recipro- 
cating file. The stroke of the file is adjustable from zero to 
4 inches and it is arranged to clear the work on the return stroke. 
The cutting stroke can be either on the upward or downward 
movement, this change being effected by simply shifting the 
crankpin to the opposite side of the crank-arm. An adjustable 
finger is provided for holding the work firmly to the table but 













/ 










/ 


OILSTONE J^P— 




~-\ SyS y\ TAPER OF 
y/y^L. X\ — DIE 




CLAMP-H LJS) Y^ 




Ma/shinery 



Fig. 17. Diagram Illustrating Method of Stoning out a Blanking Die 

allows it to be moved freely in any direction on the table. An 
air pump blows away the chips and filings and keeps the work 
and file clear, thus insuring a smooth cut. The file may be 
clamped either above or below the table, or at both ends. The 
file is supported at the free end by means of a special arm which 
carries an adjustable finger that bears against the file at the 
back. A pair of arms for holding hacksaw blades is also pro- 
vided, which may be attached to the slide in place of the file 
arms. Saws are sometimes employed for cutting out the core 
of the die. One advantage of the die filing machine, as com- 
pared with hand filing, is that straight or flat surfaces can be 
filed without difficulty because the file is mechanically guided 
and moves in a straight line, whereas, when filing by hand, it is 
difficult to do the work accurately. 

Method of Stoning Out a Die. — Stoning or lapping out a die, 
to correct slight distortions due to changes in hardening, is 



DIE CLEARANCE 



49 



often a tedious job and can be much more easily accomplished 
when using suitably placed guides or guards for the stone. As 
an example, consider a die like the one shown in Fig. 17, having 
a square hole to be stoned out. First the outside of the die is 
ground as nearly parallel with two of the sides of the square 
hole in the die as possible. Then a block A, made of soft steel, 
having two sides beveled at the same angle as the die, is set 
parallel with surface B and at the correct height. During the 
lapping operation this block A will furnish a good guide for the 
stone or lap. 

Clearance Between Punches and Dies. — The amount of 
clearance between a punch and die for blanking and perforating, 



Clearances Between Punches and Dies for Different Materials 


Thickness 
of Stock, 


Clearance, Inches 


Thickness 
of Stock, 


Clearance, Inches 














Inches 


Brass, 


Medium 


Hard 


Inches 


Brass, 


Medium 


Hard 




Soft 


Rolled 


Rolled 


Soft 


Rolled 


Rolled 




Steel 


Steel 


Steel 




Steel 


Steel 


Steel 


O.OIO 


O.OO05 


O . 0006 


0.0007 


O. 120 


0.0065 


O.O072 


O . 0084 


0.020 


O.OOIO 


O . OOI 2 


O.OO14 


O. 140 


0.0075 


O . 0084 


O . 0098 


0.030 


0.0015 


O.OOI8 


0.002I 


O. 160 


0.0085 


O . 0096 


O.OII2 


0.040 


0.0020 


O.OO24 


0.0028 


O. 180 


0,0095 


O.OI08 


O.OI26 


0.050 


0.0025 


O.OO3O 


0.0035 


O. 200 


O.OI05 


O.OI20 


0.0140 


0.060 


. 0030 


O . OO36 


. 0042 


O. 220 


0.0115 


O.OI32 


0.0164 


0.070 


0.0035 


O.O042 


O . 0049 


O. 240 


0.0125 


O.OI44 


0.0178 


0.080 


0.0045 


O . 0048 


0.0056 


O. 260 


0.0135 


O.O156 


0.0192 


0.090 


0.0050 


O.O054 


. 0063 


. 280 


0.0145 


O.O168 


O.0206 


0. IOO 


0.0055 


O . 0060 


0.0070 


O.300 


0.0155 


O.O178 


0.0220 



or the difference between the size of the punch and die opening, 
is governed largely by the thickness of the stock to be operated 
upon. For thin material such as tin, for example, the punch 
should be a close sliding fit, as, otherwise, the punching will 
have ragged edges, but for heavier stock there should be some 
clearance, the amount depending upon the thickness of the ma- 
terial. The clearance between the punch and die when working 
heavy material lessens the danger of breaking the punch and 
reduces the pressure required for the punching operation. To 
obtain the clearance between the punch and die, divide the 



50 BLANKING DIE CONSTRUCTION 

thickness of the stock by a number or constant selected accord- 
ing to the following rules which apply to different materials: 
For soft steel and brass, divide the thickness of the stock by 
the constant 20; for medium rolled steel, divide by 16; for hard 
rolled steel, divide by 14. 

Example. — What would be the clearance between a punch 
and die to be used for perforating or blanking soft steel 0.050 
inch thick? 

Thickness of stock 0.050 



20 20 



= 0.0025 inch. 



Whether this clearance is deducted from the diameter of the 
punch or added to the diameter of the die depends upon the 
nature of the work. If a blank of given size is required, the 
die is made to that size and the punch is made smaller. In- 
versely, when holes of a given size are required, the punch is 
made to correspond with the diameter wanted and the die is 
made larger. Therefore, for blanking to a given size, the clear- 
ance is deducted from the diameter of the punch, and for per- 
forating, the clearance is added to the diameter of the die. To 
illustrate, suppose we want to blank hard rolled steel having a 
thickness of 0.0625 inch (No. 16 gage) to a diameter of 1 inch. 
What would be the sizes for the punch and die? The clearance 

equals - = 0.0044 inch. As this is a blanking operation, 

the die is made 1 inch, and the punch diameter equals 
1 — 0.0044 — -9956 inch. 

A loose fitting punch will cut absolutely free from burrs up to 
a certain point, but, if it is a little too loose or a little too tight, 
ragged edges will be left on the punchings as the result. A 
general rule which is sometimes used to determine the clearance 
is to allow a clearance between the punch and die equal to 6 per 
cent of the thickness of the stock to be cut. For example, sup- 
pose a punch and die is required for cutting plain steel washers 
0.040 inch thick. Then six per cent of the thickness of the stock 
equals 0.040 X 0.06 = 0.0024 inch, which would be the differ- 
ence between the size of the punch and the die. 



DIE CLEARANCE 



SI 



Angular Clearance for Dies. — The amount of angular clear- 
ance ordinarily given a blanking die varies from one to two 
degrees, although dies that are to be used for producing a com- 
paratively small number of blanks are sometimes given a 
clearance angle of four or five degrees to facilitate making the 
die quickly. When a large number of blanks are required, a 
clearance of about one degree is used. There are two methods 
of giving clearance to dies : In one case the clearance extends to 
the top face of the die as indicated at A in Fig. 18; in the other, 
there is a space about \ inch below the cutting edge which is 
left practically straight, there being a very small amount of 
clearance. A die of this type is illustrated at B. For very soft 




Fig. 18. Sectional Views of Blanking Die Illustrating Two Methods of 
giving Clearance to the Cutting Edge 

metal, such as soft, thin brass, the first method is employed, 
but for harder material, such as hard rjrass, steel, etc., it is 
better to have a very shallow clearance for a short distance be- 
low the cutting edge. When a die is made in this way, thousand-, 
of blanks can be cut with little variation in their size, as grind- 
ing the die-face will not enlarge the hole to any appreciable 
extent. 

Fitting the Punch to the Die. — It is customary to make the 
die and harden it, and then make the punch and fit it to the die. 
After squaring the end of the punch that is to enter the die, 
the surface is colored with blue vitriol solution, or by heating it 



52 BLANKING DIE CONSTRUCTION 

until a distinct brown or blue color is visible, after which the 
desired shape is marked on the face by scribing. It is often 
considered advisable to lay out the shape by means of the 
templet or master blank, but if the templet is not of the same 
shape on its two edges, or if the shape is irregular and not sym- 
metrical, it will be necessary to place the opposite side against 
the punch from that placed against the die; therefore, it is the 
practice, in many cases, to mark the punch from the die in- 
stead of using the templet. If the face of the die is given shear 
(the purpose of which will be explained later), the punch should 
be marked before the die-face is changed. When laying out 
several punches from a die which has a number of openings, it 
is necessary to lay out the punch from the die. 

Before transferring the outline of an intricately shaped die to 
the punch, it is good practice to coat the face of the blanking 
punch with solder; then machine the solder so that it is level. 
Coating the punch with solder enables one to obtain a much 
better outline than would be possible when scribing on the hard 
steel, and the very narrow and intricate parts can be laid out 
more easily. If yg- inch of solder is evenly placed on the punch, 
it allows the die to cut a perfect impression in the solder, which 
is a great help in milling the punch, as the milling cutter can be 
brought down until it just scrapes the solder, and the cut taken. 
At the completion of the milling operation the solder is removed. 

The surplus stock on the punch is removed by filing, chipping, 
milling or planing, as the case may be, until it is but a trifle 
larger than the opening in the die. The end is then chamfered 
or beveled somewhat so that it enters the opening, and the punch 
is forced into the die a little way. It is then removed, the 
stock cut away, and the punch forced in again somewhat farther. 
This process is continued until the punch enters the die the re- 
quired distance. It is then filed or scraped until the desired fit 
is obtained. When shearing the punch through the die, be sure 
that it stands perfectly square with the top face of the die. 
Care should also be taken to see that the die does not remove 
too much stock. If the die removes a nice curling chip from the 
punch it is not removing too much stock, but if the chip cracks 



METHODS OF HOLDING PUNCHES 53 

and breaks as it is severed, it is obvious that it is removing too 
much stock, and before going any further the punch should be 
removed and reduced in size, at the point or points where the 
die was removing too much stock. It is advisable always to 
use oil on the punch when shearing it through the die. 

There are instances in which it is advisable to make punches 
somewhat differently from the method described. When the 
nature of the stock to be punched is such as to cause it to cling 
to the punch, making the operation of stripping difficult, to the 
extent that any stripper plate put on the die would be bent, or 
the end of the punch pulled off during the operation, the punch 
may be made straight for a distance that allows of grinding 
several times; then the portion immediately above this may be 
given a taper. This tapered portion of the punch is intended to 
enter the stock, but not the die. Its action is to increase the 
size of the opening somewhat, thus making the operation of 
stripping possible without endangering either the stripper or the 
punch. 

Punches for piercing and blanking copper should be polished 
quite smooth, as copper clings tightly and is difficult to strip 
from the punch. If the punch is left rough, the force neces- 
sary to strip the blank from the punch is very likely to bend it 
out of shape or to break the punch. 

Methods of Holding Punches. — Punches are attached to 
their holders in quite a variety of ways. The method may de- 
pend upon the size and shape of the punch and whether it is to 
be used singly or in combination with other punches. The 
service for which the punch is intended is another point that 
should be considered; that is, whether the material to be punched 
is light or heavy and also whether the die is for producing a 
comparatively few parts or is intended for continuous service. 
When punching heavy material, the punch must be firmly 
secured against vertical thrust in either an upward or downward 
direction, because when the punch ascends and is stripped from 
the stock, it is subjected to a heavy downward pull. If the die 
is a type intended for a small amount of work, a cheap and 
quick method of making both the punch and the die would 



54 



BLANKING DIE CONSTRUCTION 



ordinarily be employed. The personal ideas of the designer or 
toolmaker also affect the construction of punches and dies, and 
even those who have had wide enough experience to qualify 
as experts often disagree on important and fundamental points. 
Therefore, owing to the different factors which govern punch 
and die design, the practice is variable and far from being 
standardized. 




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Fig. 19. Different Types of Punches 
A number of different methods of attaching punches, which 
are commonly employed in diemaking practice, are referred to 
in the following. When only a single punch is required, it is 
ordinarily made in one solid piece, as illustrated at A, Fig. 19, 
the punch being integral with the round shank which enters 
and is clamped in the ram or slide of the press. Usually it is 
necessary to fasten several punches to a holder and then the 
construction is different. The method illustrated at B is com- 
mon, especially when the shapes of the punches are not intricate 
or very irregular. As the diagram shows, each punch passes 
through a punch plate a and bears against the punch-holder b. 



METHODS OF HOLDING PUNCHES 55 

The upper end is riveted over to prevent the punch from pulling 
out when being stripped from the stock, and the punch plate is 
held to the holder by machine screws, as shown. Evidently, a 
round piercing punch can easily be attached in this way, but if 
the shape is very irregular, the work of machining the opening 
in the punch plate is much more difficult. Furthermore, if 
thick material is to be punched, there is danger of pulling out 
the punches when stripping the stock, especially if they are not 
well riveted at the top; therefore, some diemakers only hold 
punches in this way when the openings in the punch plate are 
readily machined and the punch is intended for medium or 
light service. Another disadvantage connected with the con- 
struction illustrated at B is that if the punch is not tightly 
fitted to punch plate a, it tends to loosen. For instance, if the 
press operator should make a miscut or a "half-cut," the punch 
which is not sufficiently rigid springs to one side and either 
shears off or loosens the riveted end, thus causing trouble. 
This method, however, has been used extensively and with 
satisfactory results. 

Another way of holding punches is illustrated at C. The 
large blanking punch at the left is provided with a round shank 
which is driven tightly into the punch plate. The punch is pre- 
vented from turning by a dowel-pin driven in at d, and, in ad- 
dition, machine screws are used to prevent the punch from 
pulling out of the plate when stripping the stock. This method 
of holding a blanking punch, especially if the shape is quite 
irregular, is preferred by some diemakers, because it is only 
necessary to machine a round hole through the punch plate in- 
stead of an irregular opening such as is required when the punch 
passes through the punch plate. In some cases, two dowel-pins, 
placed as far apart as possible, would be used instead of one 
dowel at the side of the shank. If the punch were intended for 
quite heavy material, it might be advisable to rivet over the 
end of the shank, although riveting makes it more difficult to 
remove the punch, if this should be necessary. 

The diagram D, Fig. 19, illustrates how punches are some- 
times held in a dovetailed groove in the holder. The slightly 



*6 



BLANKING DIE CONSTRUCTION 



tapering key k, which is driven in at one side, holds the punch 
securely in place. The slides of some presses have a dovetailed 
slot across the lower end so that punches may be attached to 
them directly by a dovetailed fitting. This method is especially 
desirable for large punches or those subjected to heavy duty. 

Still another arrangement, which is a modification of the one 
illustrated at C, Fig. 19, is shown at A, Fig. 20. The blanking 
punch is provided with a shank and is riveted over at the top, 
but, instead of using dowel-pins to secure it in position, a slot 
or groove is planed part way through the punch-holder as the 
illustration shows. The sides of the blanking punch are made 



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Tig. 20. Illustrating Method of Attaching Blanking Punch to Punch Plate 

to fit tightly into this groove or channel, thus giving it a rigid 
support. This same method, as applied to the holding of two 
blanking punches in the punch-holder, is illustrated at B. These 
two punches are used in connection with a double-blanking die 
for cutting two blanks at one stroke of the press. In this case, 
the slot is milled along the entire length of the punch-holder and 
the punches are driven in and securely held in position in the 
same manner as indicated at A. The advantage of attaching 
an irregular blanking punch to a punch-holder in this way, as 
compared with the method illustrated at C, Fig. 19, is that it 
does away with all screws or dowel-pins and gives a rigid con- 
struction. 



METHODS OF HOLDING PUNCHES 



57 



The method of attaching a punch illustrated at A, Fig. 21, is 
similar to the method shown at C, Fig. 19, except that the blank- 
ing punch is held to the punch-holder by a shank against which 
a set-screw is tightened. The shank is spotted to receive the 
end of the set-screw, and this spot is slightly offset so that the 
punch will be drawn upward against the collar when the set- 
screw is tightened. As will be noted, the group of small pierc- 
ing punches to the right is attached by a separate punch plate 
which is screwed to the holder, as shown by the lower plan view. 




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Fig. 21. Different Types of Punches 

Some punches are simply attached to the holder by machine 
screws, dowel-pins being used to keep them in position. An 
example is shown at B, Fig. 21. This is a cheap construction 
and is usually employed when the die is only intended for tem- 
porary use. Obviously, the punch should not be held in this 
way if it is to be used on heavy stock, owing to the excessive 
downward thrust or pull when stripping the stock. For many 
operations, such as bending, curling, or cutting light blanks, 
the downward pull is light and screws may be used. Sketch C, 
Fig. 21, shows part of a bending punch which is held together 



58 



BLANKING DIE CONSTRUCTION 



by screws. Large punches for blanking, bending, drawing, or 
curling are often bolted directly to the press slide. 

Types of Piercing Punches. — Piercing punches are made in 
several different forms and attached to the punch-holder in 
different ways, as indicated by the diagrams in Fig. 22. The 
form of punch used, in any case, depends to some extent upon 
the purpose for which the die is intended. The set-screw 
method of holding the punch, illustrated at A, is not to be 




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Fig. 22. Various Methods of Holding Piercing Punches 

recommended but is sometimes used in cheaper grades of dies. 
Punches of this kind are occasionally made with taper shanks 
in order to secure a better fit on the punch-holder and lessen 
the tendency of the punch to become loose. The punch B is 
sometimes used where it is desirable to have the punch seat on 
the face of the punch-holder instead of at the bottom of the hole 
into which it is driven. This punch, of course, is more ex- 
pensive to make than one not having a collar but the construc- 
tion is much better. 



METHODS OF HOLDING PUNCHES 59 

The methods illustrated at C, D, E, and F are employed when 
a large number of punches are to be located close together or 
when it is necessary to detach them from the head without dis- 
turbing the alignment. With either of these methods the 
punch passes through a punch plate which, in turn, is secured 
to the punch-holder by machine screws. Referring to sketch 
C, it will be seen that the upper end of the punch is riveted 
over and abuts against the punch-holder, whereas punch D has 
a head which rests in a counterbored seat in the plate. The 
form shown at D is considered by many diemakers to be an 
ideal method of making and attaching a small punch of this 
kind, because it has a firm support against the upward thrust 
when punching and is also securely held while the stock is be- 
ing stripped. This method of holding is especially adapted for 
punching heavy material. Punch E has a shoulder the same 
as punch B but the upper end is secured by riveting, as the 
illustration shows. Obviously, this form cannot be subjected 
to as heavy a strain or downward pull as would be possible with 
punch D; moreover, it is objectionable because the riveted 
end must be cut away if for any reason it is necessary to re- 
move the punch. Sketch F illustrates a method of guiding and 
steadying a slender punch which is sometimes employed. The 
punch is made of straight drill rod and the upper end is riveted 
over, while the lower end is made a close working fit in the 
stripper plate attached to the die. Instead of making the punch 
straight throughout its length, it is good practice to use drill 
rod of standard size and then turn down the lower end for a 
length of about J inch and to the diameter of the hole to be 
pierced. This allows the body part of the punch to be well 
entered into the stripper plate, in which it should be a close fit, 
before the piercing operation begins, so that the punch is rigidly 
supported when at work. The body of the punch should be a 
driving fit into the punch plate and be riveted over at the upper 
end and filed flush. When made in this way, the punch will be 
rigid, even though it is used for piercing small holes, and if it is 
well supported in the stripper plate, a much smaller punch can 
be employed than would be possible otherwise. When piercing 



6o 



BLANKING DIK CONSTRUCTION 



heavy stock, it is well to insert a hardened steel disk in the 
punch-holder just above each piercing punch. This disk pre- 
vents the end of the punch from forming a depression which 
would allow the punch to slide up and down at each stroke. 

The piercing punches shown at G and II are called " quill" 
punches and are used where a large amount of stock is to be 
pierced or when the stock is thick in proportion to the diameter 




Fig. 23. Simple Method of Locating Piercing Punches in Punch-holder 

of the punch. The piercing punch is held in position by the 
quill or punch-holder h, which is driven tightly into the punch 
plate. The piercing punch is lightly driven into the holder and 
is made of drill rod, so that it can very readily be replaced in 
case it is broken. The upper end of punch G is riveted over, as 
the illustration shows. The holder shown at 77 is equipped 
with a backing screw for the punch so that the latter can be 
adjusted vertically. The punch is retained by a set-screw. 



LOCATING PUNCHES 6 1 

Locating Punches in Punch-holder. — A simple method of 
locating round, piercing punches in the punch-holder, which has 
proved very satisfactory, is illustrated in Fig. 23. The holes 
for the punches can be located, drilled and reamed very quickly, 
and if reasonable care is taken in setting, the work will be suf- 
ficiently accurate for ordinary conditions. This method is used 
when punches are secured in the punch-holder by set-screws. 

Referring to the illustration, A is the punch-holder and B is 
a holder made of cast iron, carefully machined top and bottom, 
and bored to fit the shank of the punch-holder, which is fas- 
tened in it by the set-screw C, the punch-holder resting on 
parallels. D is a locating button hardened and ground, having 
a ^-inch hole in the upper part and a j-inch hole in the lower 
part. The ^-inch hole should be ground straight and true and 
with its axis at right angles to the bottom of the button. II is 
a pilot made of tool steel hardened and ground, with a Morse 
taper shank to fit the spindle of the drill press and has a portion 
L which is made a good sliding fit in button D. (See enlarged 
detail.) G is a plug made to fit snugly in the button D and has 
a portion M, which is the same size as the body of the punch; 
it is also made to fit snugly in the templet. These plugs are 
made in a large variety of standard sizes and form a permanent 
part of the outfit. The reamer or end-mill K is made with a 
Morse taper shank and is ground so that it will ream a hole 
which shall be a drive fit for the shank of the punch. 

To lay out the holes in the punch-holder for the punches, 
proceed in the following manner: Lay out the various holes 
from the templet which was used in laying out the die, and 
drill holes ■£% inch smaller in diameter than the shank of the 
punch, to the depth that the punch is to be set in the punch- 
holder. Then the small hole shown at F is drilled and tapped 
for a button-head machine screw. The first punch-holder is 
now reamed with the reamer K and the punch is driven in place. 
The button D is then held in place with a screw E over the 
next hole in the punch-holder, the plug G placed in the button 
D, and with the templet in place on the first punch, the button 
D is located for the second hole and securely held in place by 



62 BLANKING DIE CONSTRUCTION 

the screw E. The pilot H is now placed in the spindle / of the 
drill press and the punch-holder located on the table, so that 
pilot H enters the button D. The holder is then held in place 
by the C-clamps shown, the button D removed by means of the 
bent screw-driver J, which is made from j-inch round steel, the 
pilot H removed, and the reamer A' placed in the spindle of the 
drill press, when the hole can be reamed to size; the same pro- 
cedure is followed for all the punches. In using this method it 
is, of course, necessary to see that the spindle of the drill press 
is carefully adjusted and that the table lines up properly with 
it. This same method could also be used on the milling machine. 

Locating Punches in Follow Dies. — In making follow or 
tandem dies, considerable trouble is often experienced in getting 
the small punches to line up properly with the holes in the die. 
This is especially true when the punch-holders are made of cast 
iron, as the sand-holes and soft places cause the drill to run out 
of square, which frequently makes the method of spotting holes 
through the die impossible. Another method of doing this 
work consists of placing a jig button on the punch-holder in 
exactly the same position as the hole in the die with which it is 
to mate. The punch-holder is then set in a lathe and the but- 
ton is made to run dead true. The button is next taken off and 
the hole is drilled or bored to the required size for the shank of 
the punch. This method requires very careful measurements to 
be made which, of course, involves a considerable amount of time. 

The method to be outlined in the following description does 
not require any measurements to be made. The first step is to 
make the guide A, Fig. 24. Satisfactory results can be obtained 
with guides made of cast iron, although it would be better 
to make them of steel, hardened and ground. The important 
point is to get the guide hole square with the bottom of the 
flange; the height of the guide should be | inch less than the 
height from the surface of the punch-holder to the end of the 
punch, and the wall around the hole should preferably be § inch 
thick. The flange is made about 1^ inch in diameter by \ inch 
thick and is cut away on one side to enable a hole to be made 
close to a large punch. 



LOCATING PUNCHES 



63 



The hole in the guide is the same size as the shank of the 
punch which is to be carried by the punch-holder. The next 
part to be made is shown at B; it consists of a small piece of 
cold-rolled steel about f inch long. The large diameter D is 
turned so that it will push into the guide without shake, and 
the small diameter Di so it can be entered into the hole in the 




Fig. 24. Method of Locating Punches in Follow or Tandem Dies 

die with a light tap. The small end is made about \ inch long 
and the large end \ inch in length. 

In setting up a job, the small end of the piece B is fitted into 
the die and the large end into the hole in the guide, as shown in 
the illustration. The large blanking punch is next fastened in 
the holder and then lowered into the die. Two parallel strips 
are then placed between the die and punch-holder, which are 
of sufficient height to keep the holder from striking the guide. 
The guide is then drawn up against the punch-holder to which 



64 BLANKING DIE CONSTRUCTION 

the flange is secured with two parallel clamps. The die is now 
removed and the pilot taken from the guide; the holder can 
then be turned up and spotted through the guide with a drill of 
the proper size to fit the hole. The hole is drilled to the re- 
quired depth and of a diameter g* 4 inch smaller than the re- 
quired size, the final finish being obtained with a rose reamer. 
If the reamer is a proper fit in the hole in the guide, the hole in 
the holder will be square with the surface and line up exactly 
with the hole in the die. This operation must be repeated for 
each hole that is required, and after the method has been used 
in a shop for some time, the necessary guides and plugs for any 
size of punch will have accumulated, thus saving a considerable 
amount of time and labor in making punch-holders. 

Shear of Punches and Dies. — When the cutting face of a die 
is inclined each way from the center, as at A, Fig. 25, or is made 
hollow, as at B, it is said to have shear. The cutting faces of 
dies are given shear for the same reason that the teeth of some 
milling cutters are made helical or spiral, in that the shear 
makes it possible to cut the blank from the sheet with less ex- 
penditure of power and therefore reduces the strain on the 
punch and die. Whether a die should be given shear or not 
depends upon the thickness of the stock to be cut and, in some 
cases, upon the power of the press available. When com- 
paratively thick material is to be blanked out, shear on the die 
face reduces the power required, as previously mentioned. A 
die is also given shear, at times, when the stock is not very 
thick but for the reason that it is necessary to use a small 
press. 

While it is customary to give shear to the face of the die, 
there are instances when it is advisable to leave the face of the 
die flat and give shear to the punch instead. In general, the 
shear is given to the punch when the stock around the hole is 
the desired product and the material removed by the punch is 
the scrap. The face of the die is sheared when the blank or 
that part which is cut out by the punch is the product. The 
amount of shear which a die should have to give the best re- 
sults depends not only upon the thickness of the stock but also 



SHEAR OF PUNCHES AND DIES 



65 



upon the length of the blank to be cut and the power of the 
press. 

Ordinarily the amount of shear x should equal about twice 
the thickness of thin light stock, but for heavy material the 
shear should equal the stock thickness. The exact method of 
obtaining the shearing effect depends somewhat upon the shape 
of the die. An oblong or rectangular-shaped die may be given 
shear as illustrated at either A or B. The method shown at B 
is generally considered preferable. The die-face is ground so 



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Fig. 25. Diagram Showing how Shear is Given to Cutting Edges 

that the cutting edges slope towards the center, which should 
be rounded and not sharp, because a sharp corner tends to crack 
the metal at this point. A space about \ or \ inch wide, de- 
pending upon the size of the die, is left flat at the ends. When 
a die is sheared as at B, the punch will begin cutting at both 
ends instead of at the center, and if the hole in the die is long in 
proportion to the width, this tends to give better support to 
the punch because both ends enter the die at the beginning of 
the cut; moreover, the stock is held more securely during the 
blanking operation. Some dies are given shear by simply 



66 BLANKING DIE CONSTRUCTION 

grinding them concave on the face of the grinding wheel. This 
concave or circular form is inferior to that shown at B, because 
there is less shearing effect toward the center of the die. The 
cutting edge of a round blanking die is generally given shear by 
grinding a series of three or four waves on the top surface, thus 
leaving a corresponding number of raised portions where the 
cutting action begins as the punch descends. 

As previously intimated, when the face of the punch is left 
flat and shear is given to the die, the blanks cut out by the 
punch will be approximately flat and the remaining stock or 
scrap will be bent and distorted somewhat, whereas, if the shear 
is given to the punch and the die is left flat, the order will be 
reversed; that is, the part cut by the punch will be bent and the 
rest of the stock will come out flat. This effect which the shear 
has upon the shape of the stock is utilized in some instances in 
order to cut out a blank and bend it in one operation. The 
principle is illustrated by the diagram at C, Fig. 25. The end 
of the punch is made to conform to the required shape of the 
blank; when the punch descends and cuts out the blank the 
latter is pressed in against the concave end and is bent to shape, 
thus eliminating a second operation. This method is only 
practicable for producing blanks of simple form. 

The sketch D illustrates a method of making a multiple or 
gang punch which is sometimes resorted to in order to secure 
the effect of shear. When several holes are to be punched at 
each stroke of the press, the work can be distributed by vary- 
ing the length of each successive punch an amount equal to the 
thickness of the stock or slightly greater; then, as the punch 
descends, the holes will be punched progressively instead of 
simultaneously, and, as the longest punch will have passed 
through the stock before the next one comes into action, the full 
power of the press is available for each punching operation. 

Hardening Dies. — When handling work of so diversified a 
character as the hardening of dies, it is impossible to adopt any 
set method which is not to be deviated from, as there is no one 
class of work that calls for a greater exercise of skill and com- 
mon sense than the proper hardening of dies. 



HARDENING PUNCHES AND DIES 



6 7 



The secret of success in hardening dies by the ordinary method 
consists in getting as nearly as possible a uniform heat. To ac- 
complish this the die cannot be heated very rapidly, as the 
edges and lighter portions would heat more rapidly than the 
balance of the piece. Unequal contraction, when quenching in 
the bath, follows uneven heating, and unequal contraction 
causes the die to crack. High heats cause cracks in steel. 
Then, again, high heats render the steel weak, and the result is 
that it cannot stand the strain incident to contraction of one 
portion of the steel when another portion is hard and conse- 




B- 



Machinery 



Fig. 26. Magnetic Device for Determining Correct Temperature for 
Hardening Dies 



quently rigid and unyielding. Steel is strongest when hardened 
at the proper temperature, known as the "refining heat." 

Determining Hardening Temperature. — A simple method of 
determining this refining heat, or the temperature at which the 
finest grain in the steel will be obtained, is illustrated in Fig. 26. 
The die to be tested is placed under the magnet A , from time to 
time, as the heating progresses, and when the point is reached 
where the steel has no attraction for the magnet, the die should 
be quenched in the cooling bath. If a temperature pyrometer 
is available, it is a good plan to record the temperature so that 
all dies made from this grade of steel can be heated to that 
point. If a temperature pyrometer alone is used, without the 



68 BLANKING DIE CONSTRUCTION 

magnet, readings are taken at stated intervals of approximately 
one minute apart, and then a chart is laid out by taking the 
readings as obtained from the pyrometer. This chart, if properly 
laid out, will show at the decalescent point or refining heat a 
horizontal line. 

The temperatures at which decalescence occurs vary with the 
amount of carbon in the steel, and are also higher for high-speed 
steel than for ordinary crucible steel. The decalescence point 
of any steel marks the correct hardening temperature, and the 
steel should be removed from the source of heat as soon as it 
has been heated uniformly to this temperature. Heating the 
piece slightly above this point may be desirable, either to in- 
sure the structural change being complete throughout, or to 
allow for any slight loss of heat which may occur in transferring 
the work from the furnace to the quenching bath. When steel 
is heated above the temperature of decalescence, it is non- 
magnetic. If steel is heated to a bright red, it will have no at- 
traction for a magnet or magnetic needle, but at about a " cherry- 
red," it regains its magnetic property. This phenomenon is 
sometimes taken advantage of for determining the correct 
hardening temperature, and the use of a magnet is to be recom- 
mended if a pyrometer is not available. The only point re- 
quiring judgment is the length of time the steel should remain 
in the furnace after it has become non-magnetic, as the time 
varies with the size of the piece. When applying the magnet 
test, be sure that the magnet is not being attracted by the tongs 
or other pieces of iron or steel. 

While it is possible to harden steel within a temperature range 
of about 200 degrees and obtain what might seem to be good 
results, the best results are obtained within a very narrow 
range of temperatures which are close to the decalescence point. 
The hardening temperature for both low tungsten and carbon 
steel can be located with accuracy, and the complete change 
from soft to hard occurs within about a range of 10 degrees F. 
or less. Prior to heating, it is advisable to plug all holes for 
screws or pins with fireclay or asbestos. It is also good practice 
when planing a die blank to always remove at least yg inch from 



HARDENING PUNCHES AND DIES 69 

the top face of the die blank, as this amount is generally de- 
carbonized and will not harden perfectly. 

Cooling Baths for Dies. — Cold baths are a source of endless 
troubles when hardening dies. They will not make the steel 
any harder than one that is heated to a temperature of 60 or 
70 degrees, or even warmer than this, but they will cause the die 
to spring or crack where the warmer bath would give excellent 
results. A bath of brine is to be preferred to one of water for 
this class of work, the brine being heated to the temperature 
mentioned in the foregoing. The following is a solution which 
has been found to give very satisfactory results for this purpose. 
Into pure rain water mix enough salt to float a raw potato. 
To eight gallons of the brine, add one pint of oil of vitriol. 
After hardening the die in this solution it should be dipped in 
strong, hot soda water, which will prevent it from rusting. 

Have the bath of generous proportions. When the die is 
properly heated, lower it into the bath in a vertical position, 
moving it slowly back and forth in order to cause the liquid to 
circulate through the openings, thus insuring the walls of the 
opening hardening in a satisfactory manner. The backward and 
forward movement also brings both surfaces of the piece in 
contact with the liquid, causing them to harden uniformly, and 
preventing an undue amount of "humping," as would be the 
case if one side hardened more rapidly than the other. The 
workman must, of course, exercise common sense when doing 
this class of work. If he were to swing a die containing sharp 
corners, intricate shapes, and fine projections as rapidly in the 
bath as it would be safe to do were the opening round or of an 
oval shape, it might prove disastrous to the die, as such a shape 
would give off its heat very rapidly, and as a result the fine pro- 
jections and sharp corners would harden much quicker than the 
balance of the die; as they continued to contract, the projections 
would fly off, or the steel would crack in the corners. To avoid 
this, have the bath quite warm, move the die slowly, and as 
soon as the portions desired hard are in the proper condition, 
remove the die and plunge it in a bath of warm oil, where it 
may remain until cooled to the temperature of the oil. Another 



7° 



BLANKING DIE CONSTRUCTION 



method of cooling a die so as to relieve internal strains is as 
follows: Plunge the die in the cooling bath and when it is suf- 
ficiently cold so that it can be taken hold of by the hands, with- 
draw it quickly and place it on the fire until it has become so 
warm that it will make water sizzle when dropped thereon; 
then immerse once more until cold. This is done to relieve the 
internal strains caused by hardening, and acts as a preventive 
of cracking. Most of the trouble experienced when hardening 
dies is due to one of two causes — possibly both. The first 
cause is uneven heating, the second, cold baths. 



Ei" 




Machinery 



Fig. 27. Arrangement of Oil-cooling Bath for Dies 

For dies which must retain as nearly as possible exact measure- 
ments, especially if of complicated form, pack-hardening gives 
excellent results. When hardening by this method, it is well 
to use a bath of raw linseed oil of the type shown in Fig. 27, in 
which the oil is kept from heating by being pumped through a 
coil of pipe submerged in a tank of water. If such a bath is 
not at hand, good results can be obtained, where the oil is not 
agitated, by swinging the die back and forth and moving it up 
and down in the oil. If many dies are to be hardened in this 
way, however, it is necessary to have a bath of generous pro- 
portions, or else several smaller baths, as it would not do to 
use the oil after it became hot, although oil that is heated 



HARDENING PUNCHES AND DIES 71 

somewhat will conduct the heat from steel more rapidly than 
would be supposed, and is better adapted for hardening than if 
it is extremely cold. 

Drawing Temper of Die. — A simple method of drawing the 
temper is to heat the hardened die (after the face has been 
brightened or polished) upon a heavy iron or steel plate, say, 
f or \ inch thick; this plate should be set over the fire and the 
die placed upon it with the face upward. As the die becomes 
heated, it should be moved around the plate to avoid local and 
uneven heating. The color to which the die should be drawn 
before cooling depends upon the service for which it is to be 
used. For ordinary work it should be drawn to a deep straw 
color. The bottom and top surfaces should next be ground, 
preferably on a surface grinder, and if the hole in the die has 
been slightly distorted by the hardening operation, any slight 
corrections which may be necessary can be made by oil stoning. 

Points on Heating Die in a Forge. — Manufacturing plants 
are not equipped with all the latest and most approved facilities 
for hardening, if there are only a few pieces to be treated oc- 
casionally, and, in cases of this kind, the diemaker must make 
the best of the apparatus on hand. If a blacksmith's forge is 
used, let the die be placed in the fire with the cutting face up- 
ward. During the period of heating, keep the fresh coal away 
from the die by surrounding it on all sides and on top with red- 
hot cinder coal. When turning on the blast, be careful not to 
give it too much air. The more sparingly the blower is used, 
the better are the chances of the steel becoming evenly heated 
throughout. Turn it into the fire for about a minute, then shut 
it off and let the heat soak into the die instead of blowing it in. 
This is probably the most important point. The block of steel 
must be evenly saturated with heat and kept from contact with 
cold air until it reaches the proper hardening temperature. 
Remember to blow a little and then stop the air while the steel 
absorbs the heat. While the die is being heated, prepare a pail 
of clean water, taking the chill from it, that is, heating it until 
lukewarm. The die, held in one hand with tongs, is then 
plunged into the water and kept moving all the time; when the 



72 BLANKING DIE CONSTRUCTION 

die is cool enough, take hold of it with the other hand and stir 
the water with it until both water and die arrive at the same 
degree of heat. Now instead of taking the die out of the water 
and reheating it over the fire or letting it cool in the air, just let 
the water and steel cool off together. 

Hardening Punches. — If punches are to be hardened — and 
this is generally considered best — they should be very carefully 
heated. It must be borne in mind that punches are subjected 
to a great strain; consequently, they should be heated uni- 
formly, and to as low a temperature as will give desired results, 
thus making them as strong as possible. Heat slowly to avoid 
overheating the corners, as these are subjected to the greatest 
strain. The distance a punch should be hardened depends on 
the shape and size, and the use to which it is to be put. If it is 
a piercing punch that is long and slender, it should be hardened 
the entire length to avoid any tendency to bend or upset when 
in use. If it is of a form that insures sufficient strength to re- 
sist any tendency to upset when in use, then it need not be 
hardened its entire length. A simple method of hardening a 
punch to prevent warping, which is recommended by an expert 
diemaker, is as follows: The face of the punch for about f inch 
up is held in molten lead until it is an even red color all over. 
It is then quenched. This hardens the face of the punch for 
about f inch up and leaves the back soft. This method has 
very little tendency to warp the punch, the large part of it, 
which is cold, or comparatively so, counteracting it. Experience 
has shown that if properly done, the punch comes out straight 
and parallel and not warped at all. 

Pack-hardening is an admirable method of hardening punches 
for most work, but for piercing punches, it is not recommended, 
as the whole structure of the steel should be as nearly alike as 
possible. Such punches should be heated in a muffle furnace, 
or in a tube in the open fire, turning the work occasionally to in- 
sure uniform results, for not only can we heat a piece more 
uniformly if it is turned several times while heating, but a fact 
not generally known is that a cylindrical piece of steel heated 
in an ordinary fire without turning while heating will many 



HARDENING PUNCHES AND DIES 73 

times show softness on the side that was uppermost in the fire, 
no matter what care was taken when heating and dipping. If 
it is reheated with the opposite side uppermost, that will be 
found soft if tested after hardening, while the side that was soft 
before will be hard. The smaller the punch the more attention 
should be given to the condition of the bath. Luke warm brine 
is the best. Work the punch up and down and around in the bath. 

Tempering Punches. — It is the practice of many diemakers 
to draw the temper of comparatively long slim piercing punches 
to a full straw on the cutting end, but to have the temper lower 
further up the punch. Better results follow, however, if the 
punch is left of a uniform hardness throughout the entire length 
of the slender portion, as it is then of a uniform stiffness, and 
the liability of springing, especially when punching stiff or 
heavy stock, is reduced to a minimum. It is generally con- 
sidered good practice to temper the punch so that it is somewhat 
softer than the die; then, if from any accident the two come in 
contact, the die will in all probability cut the punch without 
much injury to itself. There are exceptions to this practice,, 
however. In many shops where large numbers of dies which 
are hardened are used, it is customary to have the one which is 
the more difficult to make the harder, so it will cut the other if 
they come in contact with each other. 

Punches should be carefully examined after hardening and 
tempering, and those which have been bent or sprung in the 
hardening should be carefully straightened. Piercing punches 
in compound dies are steadied by the knockout while operating 
on the stock. The punch is made a sliding fit in the knockout, 
and the knockout is also made a sliding fit in the die. When 
perforating thick metal where the strain on the press is great, a 
good method to reduce the pressure is to make each second 
punch lower than the preceding one an amount equal to the 
thickness of the stock. This, as can be seen, will reduce the 
pressure, as half the punches are through the stock before the 
remaining half operate. When heavy stock is being blanked or 
pierced, punches are not required to fit as snugly as when the 
metal is thin. 



74 BLANKING DIE CONSTRUCTION 

It is generally found after hardening small piercing punches, 
that although the holes in the punch-holder are true with the 
die, the punches do not line up. This is because they have bent 
slightly in hardening. They can usually be brought into align- 
ment by giving those that do not enter half a turn, but if this 
does not locate them correctly, they should be removed and 
straightened. When a large and a small piercing punch are too 
close together to allow of both being set in the punch-holder, 
the smaller punch is set in the larger one, and securely held 
in position. 

When Punch and Die should be Hardened. — There are 
various opinions among practical men as to the advisability of 
hardening punches. For most jobs it is the custom to do so, 
though there are some mechanics who consider it advisable to 
harden them, and others who do not. There are instances 
where punches work well either way, and in such cases it is, of 
course, a matter of opinion. The blanking or cutting dies used 
on comparatively thin stock, such as tin, brass, aluminum, iron, 
steel, copper, zinc, etc., are ordinarily hardened and tempered 
to suit the work, and the punch is left quite soft, so that it can 
be "hammered up" to fit the die when worn. This practice is 
followed in some plants for all metals less than -£§ inch thick 
which are not harder than iron or very mild steel. After the 
end of the punch has been upset by hammering, the punch and 
the die are oiled and forced together, which causes the hard die 
to shave the punch to a close fit. If the die is dull, it should be 
sharpened prior to this shearing operation. For some classes of 
work, the punch is made hard and the die soft. Both the punch 
and die should be hardened when they are to be used for blank- 
ing thick iron, steel, brass, or other heavy metals. 

Correcting Mistakes made in Dies. — Should the workman, 
through misunderstanding or carelessness, make the opening in 
a die too large at any point, he should not attempt to peen the 
stock cold, as is sometimes done, for while it is possible to do this 
and then finish the surface in such a manner that it will scarcely 
be noticeable, the stock directly below where the peening took 
place will almost surely crack during the life of the die. Should 



REWORKING WORN DIES 75 

the mistake referred to occur, heat the die to a forging heat, 
when the stock may be set in without injury to the steel. When 
setting in, a blacksmith's fulling tool may be used; this is 
placed on the face of the die and struck with a sledge. If there 
is objection to disfiguring the top surface of the die, this method 
cannot, of course, be used. It is never good practice to bend, 
set in, or otherwise alter the form of steel when cold, if it is to 
be hardened, as such attempts nearly always end in a manner 
entirely unsatisfactory. 

Reworking Worn Dies. — When a die becomes worn so that 
the opening is too large, or the top edge of the walls of the open- 
ing are worn so that the die is "bell-mouthed," it may be heated 
to a forging heat, set in with a fulling tool, or a punch of the 
desired shape, after which it is reheated to a low red and an- 
nealed. After annealing it is reworked to size. This rework- 
ing, if care and judgment is used, gives excellent results, and 
effects a considerable saving, as otherwise it would be necessary 
to make new dies, while the die may be reworked at a fraction 
of the expense of a new one. 

When making a sectional die, it is possible, in case the opening 
is a trifle too large, to work a little stock off the faces that come 
together, provided the outer edges have not been planed to fit 
the holder; also, if it is allowable, these surfaces may be cut 
away the desired amount, and a strip of stock of the proper 
thickness placed between the die and holder. Considering the 
liability of a mistake taking place when a beginner is doing work of 
this kind, it is, generally speaking, advisable to leave the fitting 
of the die to the holder until the opening has been worked to size. 

Stripping Stock from Punch. — When punches are operated 
on sheet stock, the latter will be carried upward when the punch 
ascends, unless there is some device to prevent this. The 
simplest arrangement for stripping the stock from the punch 
and one that is applied to most blanking dies, consists of a plate 
which is attached to the die (as illustrated in Fig. 1, Chapter 
I), and has an opening for the punch to pass through. Beneath 
this stripper plate there is a passage-way or opening through 
which the stock is fed. Obviously, the space between the die 



76 BLANKING DIE CONSTRUCTION 

face and stripper plate must be greater than the thickness of 
the stock to permit the latter to be fed along easily. As the 
result of this play between the stripper plate and die the stock 
is distorted to some extent by the action of the punch. This 
distortion, in many cases, does not cause trouble, especially 
when the die simply cuts out plain blanks, but when a follow 
die is used and flat accurate blanks are required, or when the 
operation is that of piercing a number of holes in sheets or flat 
plates, it is often necessary to hold the stock firmly against the 
die while the punches pass through it, in order to prevent any 
wrinkling or buckling. 

Stripper Attached to Punch. — One method of preventing the 
stock from being wrinkled or distorted by the action of the 
punch is illustrated in Fig. 28. The stripper plate M is fastened 
to the punch-holder instead of to the die, and it is backed up by 
a stiff coil spring at each corner. On the downward stroke of 
the press, the stripper plate presses the stock firmly against the 
die, holding it level while the punches perform their work. 
The stripper is so located that the punches do not come quite 
flush with its lower face, so that the stock is subjected to pres- 
sure before the punches come into action. As the stock is fed 
through the die it is guided by means of small pins N at each 
end of the die. The stripper should not fit. the punches closely 
because if the operator should make a miscut or if a piece of 
scrap punching should get under the stripper, it would cause it 
to tilt and probably break the small punches. With a die of 
this type the difficulty connected with wrinkled work is over- 
come. On the other hand, when a follow die is made with a 
fixed stripper of the usual form, the work is distorted somewhat, 
so that the location of pierced holes relative to the outer edges 
of the blanks is not always sufficiently accurate. As the die 
illustrated in Fig. 28 was made without guide pins for holding 
the punch and die in alignment, straps S were used to hold up 
each end of the stripper plate in order to expose the ends of the 
punches when aligning them. These straps were used by forcing 
the stripper upward and inserting the ends of the straps in the 
holes T, as indicated by the detail view. 



CAM-ACTUATED STRIPPERS 



77 



Presses with Cam-actuated Strippers. — Owing to the tend- 
ency which stationary stripper plates attached to dies have to 
distort pierced sheets, etc. (as explained in the foregoing), some 
presses are equipped with cam-actuated stripper plates. The 
stripper plate is attached to vertical rods which extend up above 
the press slide. When the press is in operation, the stripper, 
which is actuated by cams on the press shaft, descends first 
and clamps the stock before the punches enter the work. As 



STRAP AS USED WHEN 
[SETTING UP IN PRESS 



JH 



^ 



a 



CHECK SCREW 




•FOR DRIVING OUT PILOTS 



?5"f I | 1"~ 

I 1 ! 

Mil I 

I.I I 



I 

BLANKING PUNCH 
I 

u 



u 







ItLl 



TO GUIDE STOCK 



O 7 V/-PILOT PINSV PIN T0 GUIDE ST0CK 

^EL 



i i 
i i 



Machinery 



Fig. 28. Stripper Attached to Punch to Flatten out Stock and Hold it 

Securely 

the stripper plate is suspended above the die, a clear space is 
left between the punch and die, so that the operator has an un- 
obstructed view. The stripper plate moves up and down with 
the punches, so that the latter may be made shorter than would 
be possible with a stationary stripper, thus increasing their 
rigidity and durability. 

A smaller hole in proportion to the thickness of the stock may 
be pierced when using a stripper of this kind, because of the 
close support which the stripper gives the punches up to the 



78 BLANKING DIE CONSTRUCTION 

point where they enter the stock. Another advantage con- 
nected with the use of the cam-actuated stripper is that of 
avoiding the blow from the stock which the lower side of the 
stationary stripper plate receives upon the upward stroke of 
the punch, owing to the necessary play between the die and the 
stripper plate. This method of stripping the stock is particu- 
larly adapted for gang punching and perforating operations, 
especially when the punches are small in proportion to the 
thickness of the stock and when it is essential to guide them 
close to the surface of the work. 

Pilots or Guide Pins for Punches. — The pilots or guide pins 
which are placed on the ends of some punches for aligning the 
stock before blanking, by entering holes that have been pierced 
previously, should be made slightly smaller than the hole in 
the blank and should be straight for the thickness of the stock, 
and then rounded off similar to the point of an acorn. The 
heads of all guide pins should be turned true with the shank. 
Care should be taken to see that the guide pins are also ex- 
actly in line with the pierced holes. If they are not in line they 
have a tendency to twitch the metal around, so that after a few 
blanks have been punched, the strip will not be in alignment 
with the die. Precaution should be taken to see that the stock 
does not cramp between the guide pins and the stop, or be- 
tween the guide pins and the back gage, because if this is neg- 
lected it will generally cause trouble. When the pierced holes 
are very small the punch should be provided with a spring 
guide pin, so that if the pin misses the pierced hole in the blank, 
it will spring back into the punch and nothing is spoiled except 
the blank. After having completed the die and punch, before 
taking them to the press, see that all guide pins, when -in the 
punch, locate accurately in the pierced holes, and also see that 
all the punches line up perfectly. 

Punch Troubles and Remedies. — Small perforating punches 
which have annular marks left on them from turning or polish- 
ing are much more liable to fracture than those having marks 
which run parallel with the punch, especially when perforating 
heavy stock. This is due to the fact that the metal presses 



PUNCH TROUBLES AND REMEDIES 70 

into the minute lines or grooves, thus increasing considerably 
the force required for stripping. As is generally known, most 
punches when used on heavy metal arc broken while stripping 
the stock and not while perforating itj therefore, the stripping 
should be made as easy as possible. The stripping can be 
facilitated by making Lhe punch slightly tapering towards the 
top, although this is not practicable for small punches, because 
the strength ol the punch would be reduced too much. When 
the face ol a punch which is used on heavy metal lends to chip 

oil, it is caused either by the punch being too hard or the 

diameter ol the die hole being too near to the diameter of lhe 

punch. If the stripper plate is not parallel with the die, this 
will also cause broken punches. ICven though the error in 
alignment is small, the constant bending action that the punches 
must undergo every time the stock is stripped lends lo shorten 
their life. Sometimes the shipping is much harder on one end 
of the die than Oil the other, because more holes are perforated 
at one end. In such a case, Special care should be taken to See 
that the stripper plate starts the slock from the pun* lies evenly 
and uniformly. The making of small perforating punches re 

quires attention to minute details in order to secure 1 the best 

results. For instance, a punch should not be made with sharp 
corners but rather with rounded corners. 1 1 should never he 
Undercut, because even il it is scored very slightly this will 
establish a breaking point. 

When a die has a number of large and very small punches, il 
is often advisable to make the large ones long enough lo per- 
forate the slock and just enter lhe- die before lhe small ones 
touch the metal, especially if the stock is heavy, because lhe 
jar resulting from lhe action ol lhe large punches may shift the 
stock slightly which would tend to break lhe smaller punches, 
provided they entered the stock at the same lime. This method 
of varying lhe lengths ol punches has often been used lo 
advantage in dies having a. large number of punches, and has 
made it possible lo use a certain press which otherwise would 
have lacked lhe necessary capacity, inasmuch as lhe pressure 

required for punching is distributed somewhat. When locating 



80 BLANKING DIE CONSTRUCTION 

punches in the holder, one of the principal points to consider is 
that the stripping strain should be as equally divided in re- 
lation to the punch-holder shank as possible; the surface of 
the holder which bears against the slide of the press should also 
be of such a size that the face of the slide will not be injured. 
Punches often shear themselves because a depression has been 
worn in the face of the slide and for that reason the holder is not 
properly supported. Inaccuracies in laying out pilot holes in 
punches and the use of eccentric pilots in order to make them 
register properly have also been the cause of much spoiled 
work. The trouble is that when the punch is sharpened, this 
necessitates the removal of the pilot which often is not replaced 
in the same position, and, consequently, it does not engage 
properly with the pierced holes in the stock. 

It sometimes happens that the blanking punch or certain per- 
forating punches are of such a shape that they tend to incline 
to one side and cause shearing when passing through the metal, 
thus injuring the edge of both punch and die. This is caused 
by the shearing thrust not being equal on all sides. For in- 
stance, the shearing strain from two long sides sometimes crowds 
the punch over toward the shorter side. To prevent this trouble 
the face of the punch should be ground to a slight angle so that 
it enters the shorter side first; then this side will be backed up 
by the die to take the thrust when cutting the remaining part 
of the blank. 

Points on Making Compound Dies. — Compound dies are 
made without clearance, and the blanks are ejected by the 
knockout as soon as the punch leaves the die. The piercing 
holes in the punch, however, should be taper reamed and larger 
at the top, so that the piercings will pass up through the punch 
easily. The throwing out of the piercings from a compound die 
is aided by setting the die in an inclined press. If a double 
compound die is required to produce two blanks on one stroke 
of the press, care should be taken to see that the knockouts are 
ground to the same height, and also that the blanking punches 
are perfectly level, so that both blanks will be flattened alike. 
The spring or rubber pad which operates the knockout in the 



STOP-PINS FOR DIES 8 1 

compound die should be adjusted tighter than necessary to in- 
sure the blanks being removed. The knockout should just 
bring the blank to the surface of the die. 

Stop-pins for Dies. — The stop-pin on a die is a device for 
controlling the position of the stock as it is fed through for each 
successive stroke of the press, so that the spacing of the open- 
ings cut into the stock will be uniform and a predetermined 
distance apart. The design and adjustment of stop-pins for 
blanking dies is an important branch of die work that affects 
both the quality and the quantity of the output of the press. 
There are many different types of stop-pins, such as the plain 
fixed stop-pin; the bridge stop-pin; the simple latch; the 




3SX 



Machinery 



Fig. 29. A Plain Fixed Stop-pin 

spring toe latch; the side swing latch; the positive heel-and- 
toe latch, etc. 

These devices, with the exception of the first, can be used with 
either hand feed or automatic roll feed. The ideal output of 
one blank for every stroke the press can make in a day is never 
realized with single dies, and delays which arise from many 
sources have to be studied carefully and eliminated so far as 
they contribute to unnecessary expense. In addition to im- 
proper design and poor adjustment of the stop-pin, other causes 
of small output are: lack of skill; inconvenient arrangement of 
the new stock, the blanks and the scrap; inefficient methods of 
oiling the stock; and poorly made or poorly designed dies. A 
skillful operator will usually arrange the stock distribution quite 
well, but the design and adjustment of the dies and the stop- 
pin usually devolve upon the toolmaker. 



82 



BLANKING DIE CONSTRUCTION 



Plain Fixed Stop-pin. — The plain fixed stop-pin, which is the 
simplest type, is indicated in Fig. 29. With it the operators be- 
come so expert that they are able for several minutes at a time 
to utilize every stroke of a press making 150 revolutions per 
minute. This stop is best suited to the use of strip stock in 
simple dies, because a miss will then cause no serious delay. 
The time between finishing one strip and starting the next 
affords the necessary rest for the operator. The concentration 
required is very intense — especially for the novice. When but 





Machinery 



Fig. 30. (A) Fixed Stop-pin Set close to Blanking Die Opening. (B) Ex- 
ample Illustrating Application of Stop-pin Set as Shown at A 

a few blanks are made from a die at one time, and when changes 
of dies are frequent, this simple stop-pin is the most economical. 
Of course, it would not be feasible to use this stop-pin for coiled 
stock and expect the operator to finish the coil without a rest 
or a miss. There is, however, one method of using this stop 
which permits of a maximum output; that is to allow no metal 
between the blanks. Then the stop-pin will extend clear up 
to the die and be high enough so that the stock cannot jump it. 
Each blank will then part the scrap at the stop-pin and allow 



STOP-PINS FOR DIES 



83 



the stock to be pulled along to its next position. This arrange- 
ment is shown at A in Fig. 30, with the stock parting at the 
pin P. This method is widely used on simple work where the 
edge of the blank does not have to be perfectly uniform. Small 
drawn cups are made in this way. The blank is cut by the first 
punch and held by it while a second punch, within the first, 
draws the blank through another die and forms the cup. This 
is shown in Fig. 30 at B. The stock feeds to the right and 
each cup, as formed, pushes the one ahead of it through the die 



o 




o 



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r-ff 

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r -F=p-T-"=P^-" 
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--"=KgF : 

b m 

KH-3 
KgCJ 



Machinery 



Fig. 31. Improved Form of Fixed Stop-pin 

as indicated by the dotted lines. Where the die has least to 
cut it will wear away most on account of the thin pieces of 
stock that crowd down between the punch and the die. 

The common way to make a fixed stop-pin is to bend over a 
piece of steel rod and drive it into the die. The difficulties and 
disadvantages connected with making a bent stop-pin are as 
follows: First, the difficulty of bending the pin at right angles 
without breaking it or bending the part to be driven into the 
die; second, after the pin has been made and hardened it is apt 



8 4 



BLANKING DIE CONSTRUCTION 



to break in driving it home to its place in the die because of its 
uneven shape; third, in driving the pin into the die it is liable 
to swing around out of its proper position, making it necessary 
to knock it around again and thus increasing the chances of 
breaking it. Every time the die is ground, this difficulty is ex- 
perienced and the result is frequent breakage and consequent 
loss of time in waiting for new stops. All these difficulties are 
overcome by making the style of pin shown in Fig. 31. This is 
simply a shoulder pin turned to a nice snug fit in the die. The 
shoulder, which acts as the stop for the stock, may be made larger 




1 



Machinery 



Fig. 32. Stop-pin of the Bridge Type 

or smaller in diameter according to the width of scrap desired 
between blanks. This stop is quickly and easily made, is easily 
taken out and put back again after grinding the die, and will 
last as long as the die itself. It is a good idea to cut a hole 
through the stripper A directly over the stop-pin as shown at 
G, so that the operator can see the pin when the press is in 
operation. 

Bridge Stop-pin. — The bridge stop-pin, shown in Fig. 32, is 
easy to operate and simple in design. The stop-pin P projects 
downward from a bridge B that extends over the stock which 



STOP-PINS FOR DIES 



85 



is fed to the left. Provision is made for the blank (or scrap, as 
the case may be) to fall out under the bridge. The use of this 
type of stop-pin is limited to that class of work which cuts the 
stock clear across and uses its edges as part of the finished blank. 
As here shown, the scrap is being punched through the die, and 
the blank, when cut, falls down the inclined end of the die. 
When the blanks are simpler and have straight ends, the die 
may be so arranged that each stroke finishes two blanks, one 
being punched through the die and the other falling outside 
down the incline. Little skill is required of the operator; he 
simply has to be sure to push the stock up to the stop-pin at 
each stroke. 




Machinery 



Fig. 33. Simple Latch Form of Stop 

The Simple Latch Form of Stop. — The simple latch is shown 
in Fig. 33. It is suited for dies that have pilot-pins. The latch 
is lifted by the down stroke of the punch and is lowered again 
as the punch rises. Hence it is evident that, if used with dies 
without pilot-pins, the punch must reach the stock and hold it 
before the latch lifts. When its lifting is thus delayed it will 
lower before the punch withdraws from the stock and will fall 
in the same place it lifted from so that the stock cannot be fed 
along. On the other hand, if a pilot-pin is used, which enters 
the guide hole just before the latch lifts, the latch may be set 
to lift before the punch reaches the stock. It will then fall after 
the punch withdraws from the stock, and sufficient time may be 
allowed for the operator to feed the stock along. This device is 



86 



BLANKING DIE CONSTRUCTION 



best suited for use with automatic feed rollers because the 
timing of the operations is uniform; if the operator does not pull 
the stock with uniform speed the latch is apt to drop too soon 
or too late. Another manner of operating this simple latch is to 
give it its motion by means of a cam or eccentric on the press 
shaft. When thus driven its motion can be very carefully 
timed, irrespective of pilot-pins. This style is also best suited 
for automatic roll feed. New presses are often provided with 
this attachment. 

Another simple form of latch which differs somewhat from the 




-DIE BOLSTER 



I! H 
ll II 
II l| 

L_4j bed of press 

tt-3 



Machinery, X. Y. 



Fig. 34. Latch which is Operated by Slotted Arm Attached to Punch 

one just described is illustrated in Fig. 34. There are two 
brackets A which form bearings for rod C. The stop is at- 
tached to rod C by a split knuckle D, this knuckle being held to 
the rod by means of the cap-screw K. Two washers E are 
fastened to each end of the rod on the outside of the brackets, 
to obviate any longitudinal movement, but allowing it to rotate 
easily. The stop can be adjusted through the knuckle D by 
means of the adjusting nuts F. The manner in which this stop 
operates is as follows: As the ram of the press ascends, the arm 
H, which is fastened to the ram, as shown, and has a longitudinal 



STOP-PINS FOR DIES 



87 



slot in it, raises the pin G, which extends through the rod C. 
As this pin is lifted it rotates the rod C and, consequently, 
raises the stop against the tension of spring 7. "When the stop is 
raised, the feed-rolls force the stock through the die, but the 
stop descends before the stock has been fed the required dis- 
tance. The feed used is the ordinary ratchet feed and is set so 
that it feeds jq inch further than the required distance to com- 
pensate for any slip, such as often takes place in ratchet feeds 
which are used for punch and die work. 










— 1 — 



Macltinrry 



Fig. 35. Latch Stop which is Operated by Feeding Movement of Stock 

Latch Stop Operated by Stock. — The stop shown in Fig. 35 
is excellent because of its simplicity, and also because of the 
great variety of work to which it may be applied. This stop is 
of the latch variety, but it differs from most stops of this type 
in that it requires no mechanism to lift it. It is not operated by 
the action of the press nor by the punch, as is generally the case 
with latches. A hole is drilled through the stripper A to re- 
ceive the pin K which passes through a hole in the stop C. The 
stop swings upon this pin. A light flat spring D is fastened to 
the top of the stripper so that the end of the spring rests on top 
of the stop. In securing this spring to the stripper, it is only 



88 



BLANKING DIE CONSTRUCTION 



necessary to place one end under the head of the screw E with 
a piece of the same material under the opposite side of the 
screw as shown in the plan view. By this method the spring 
can be quickly and easily attached or removed, and a straight 
piece of spring material can be used. The stripper should be 
cut off at the stop end as shown at L so that the stop will be 
outside of the stripper and in full view of the operator. 

The action of this stop is as follows: The stock F is fed to 
the left, and as the punched strip passes the stop, the point of 




Machinery 



Fig. 36. Spring Toe Latch Stop 

the stop M drops or rather springs into the hole made by the 
blanking punch. The operator then pulls the strip back against 
the straight outer edge of the stop, and holds it there until the 
next blank is punched. This process is repeated at each stroke 
of the press, the scrap between the blanks being pushed past 
the stop each time and then pulled back against it. The inner 
beveled edge of the point M causes the stop to lift as the scrap 
between the blanks is pushed against it, while the outer edge, 
which is at right angles with the die, prevents the stop from 



STOP-PINS FOR DIES 



89 



lifting when the edge of the scrap is pulled back against it. It 
will be evident from this that a double movement is required, 
i.e., to first push the stock ahead more than the required distance 
and then pull it back into contact with the stop. 

An operator can make about 40,000 blanks per day with 
dies fitted with this form of stop on a press making about 100 
strokes per minute. These stops are used only on hand-fed 
work. 

The Spring Toe Latch. — The spring toe latch involves but 
little change from the simple latch. Fig. 36 shows it clearly 
with an enlarged detail of the spring toe. This latch may be 
used very successfully with hand feed and there is little danger 




Fig. 37. The Side Swing Latch Stop 



of the stock getting by it too fast. Its operation is as follows: 
As the punch lowers and starts to cut the blank, an adjustable 
screw on the ram or punch plate lifts the latch. Its spring toe 
snaps forward and when the latch lowers, it rests on the scrap 
left between two blanks; hence it cannot fall back into its 
former place. When the operator pulls the stock along, the 
latch toe drops into the next hole and brings the stock to a stop 
at the proper point, compressing the light spring S as it does 
so. This design is simple, rigid and effective. The spring toe 
here shown is preferable to the design described in the following 
because it is light and requires but little tension on the stock to 
bring it to a stop. 



go 



BLANKING DIE CONSTRUCTION 



The Side Swing Latch. — The side swing latch shown in Fig. 
37 is but a modification of the latch shown in Fig. 36. When 
the punch descends, an adjustable screw hits lever L and lifts 
the latch. The whole rod R then springs forward till collar C 
stops against B. When the latch lowers it rests on the stock 




O 




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J 



-PUNCH 
PILOT D 




Machinery 



Fig. 38. Another Stop of the Side Swinging Type 

as did the spring toe latch. As the stock is pulled along, the 
latch drops into the next hole and acts as a stop again. With 
this style of latch the tension on the stock must be greater than 
with the spring toe latch, because the whole rod R has to be 
pulled along against the spring Q until collar D engages stop E. 



STOP-PINS FOR DIES 9 1 

If this design were modified, however, so that the side bearings 
were used only for allowing the latch to swing, the toe could be 
constructed like the spring toe latch and would then be quite 
as effective as this type, though not so rigid. 

Another design of side swinging latch is shown in Fig. 38. 
This stop mechanism consists of a latch or trigger A which is 
pivoted on the pin B. The latch works in a tapered slot in the 
stripper plate which allows it a sidewise movement of about 
3 X 2 inch. A helical spring C pulls the point of the latch down 
and tends to hold it on the side of the slot nearest to the ad- 
vancing stock. A trip-screw D is screwed into the upper mem- 
ber of the die directly over the latch, and is so adjusted that it 
will cause the point of the latch to be raised as soon as the punch 
has started operating on the stock. The method by which this 
mechanism operates is as follows: When the stock is pushed 
forward against the latch, the latter is moved over to the far 
side of the tapered slot and the stop locates the stock in the re- 
quired position for punching. As soon as the punch engages 
the stock, the trip-screw D strikes the latch and raises its point 
out of contact with the stock; then the spring C pulls it to the 
opposite side of the tapered slot so that when the punch rises 
and the latch is allowed to drop, the point comes down on top 
of the stock instead of in the hole produced by the blanking 
operation; consequently, the stock can be pushed forward un- 
til the stop drops into the next hole and the movement of the 
stock is then continued to the position for the next punching 
operation. The point of the latch is beveled at the back to pro- 
vide for withdrawing the stock if necessary. The sliding stop 
E is placed in the stripper plate to locate the end of the stock 
in the proper position for the first operation with progressive 
blanking dies. 

Positive Heel-and-toe Latch. — While the swinging latch 
type of stop-pins relies on gravity or a spring to bring them back 
in position, the heel-and-toe latch is positively operated. Its 
distinctive feature, which recommends it for use on a large 
variety of work, is that it is impossible for the stock to slip by 
it faster than one blank per stroke of the press. This is a very 



92 



BLANKING DIE CONSTRUCTION 



important matter when combination or gang dies are being 
used, because of the pilot-pins on the punches. If the stock 
slips too far, the guide holes, previously pierced, pass beyond the 
pilot-pins, and when the punch descends, the pilots punch their 
own holes, throw down a heavy burr, and cause a delay — if 
nothing more serious. 

The upper view in Fig. 39 shows the catch in position to stop 
the movement of the stock at its point A. The stock is being 
fed to the right. The conical-pointed pin B is pushed by the 
spring S so that it engages a conical depression C in the end of 




Fig. 39. Positive Heel-and-toe Latch which Prevents Stock from Moving 
more than One Blank for Each Stroke of the Press 

the catch. By this means the toe of the catch is pressed against 
the die. As the punch descends to cut the next blank, an ad- 
justable screw on the punch plate presses on the top of the 
catch at D and causes the heel to lower and the pin B to dis- 
engage from the notch C; the position of the latch is then as 
shown in the lower view. Its heel E has been lowered into the 
hole left by the previous blank and it is held in this position by 
the pressure of the point of B. While this is sufficient to hold 
the catch in its new position, it offers but little resistance to its 
return to the original position. The stock may now be moved 
along. The metal K, left between two successive blanks, en- 
gages the heel E of the latch and lifts it easily. This causes the 
notch C to engage with the pin B and the catch snaps back into 



STOP-PINS FOR DIES 93 

its first position. The toe A falls into the new opening R, and 
M comes to a stop against it. Since the metal K, between two 
successive blanks, cannot pass the heel of the latch without 
raising it, and since the heel E cannot rise without lowering the 
toe A far enough to catch the stock, it is evident that the action 
is positive; hence the stock cannot jump ahead faster than one 
blank at a time. 

In constructing a stop of this kind, care must be taken to 
allow under the heel E but little more height than the thickness 
of the stock. The length of the catch from toe to heel should 
be less than the opening left by one blank; then there will be 
no difficulty in starting the new ends of strips or coils. If 
necessary, however, the catch may be made so as to measure a 
little less than two (or more) openings in the stock. In such a 
case the catch would have to be tripped by hand until the first 
piece of stock A', between two blanks, had passed under the 
heel E. This would cause delays which would amount to con- 
siderable in the case of strip stock. 

This style of stop has been used successfully with gang dies 
cutting blanks from brass g 1 ^ mcn thick, and cold rolled steel 
g X 4 inch thick. In the case of the steel blanks, reels were used 
and the scrap was wound on a reel as it came from the die. By 
keeping the proper tension on the scrap, the stock was pulled 
through the die and kept against the stop. Four thousand 
blanks per hour were made by this means. In view of the thin 
stock used and the fact that the dies were of the combination 
type, this was considered very good. The stop had to be set 
accurately because the thin stock prevented the pilot-pins from 
shifting it much when aligning. Other precautions taken on 
account of the thin stock were to make the toe broad and to fit 
the stripper close to the front edge of the toe. 

Starting Stop for Follow Die. — The devices so far described 
serve to stop the stock when it has passed the blanking punch, 
but there are many cases where two or more operations are per- 
formed on a piece before it reaches the blanking die and the 
usual stop-pin. The operator usually gages the proper positions 
by watching the end of the stock through openings in the stripper, 



94 



BLANKING DIE CONSTRUCTION 



but it is better to have temporary stop-pins that can be used 
for that purpose. Fig. 40 shows a starting device for a follow 
die with two punches. When starting a strip the button B 
should be pressed. This brings into action the temporary stop 
S, which locates the stock properly for the first operation. It 
is then released and springs back out of the way. The stock is 
then advanced to the regular stop-pin. As many of these side 
stops may be used as are necessary. Not only do they save 
annoyance and time, but they add to the life of the dies by pre- 
venting the partial cuts due to the stock entering too far at the 
start. 




Machinery 



Fig. 40. Stop for Starting Stock in a Follow Die 

Position of the Stop-pin. — The exact position of the stop-pin 
or that part of the pin which engages the stock depends, of 
course, upon the lay-out of the die and the amount of stock that 
is to be left between the punched holes. The width of this strip 
or bridge w (see sketch A, Fig. 41) between the punched hole is 
usually approximately equal to the thickness of the stock; it 
should not be less than this amount and for very thin material 
should exceed the thickness slightly. When there is not suf- 
ficient stock between the openings, the punch, which tends to 
draw the material in when passing through it, may actually 
draw it to such an extent as to cause damage. While it is com- 
mon to allow the thickness of the stock, this rule should not 
always be applied. For instance, when narrow strips, | inch 



STOP-PINS FOR DIES 



95 



wide by 3 inches long, were blanked out crosswise of the strip, it 
was found that by allowing only the thickness of the metal the 
punch sheared off toward the scrap side because the end cuts 
were so narrow that they did not support the punch against 
the thrust resulting from the shear on the solid side of the strip. 
When using dies of the general shape referred to, it is advisable 
to allow at least i| times the thickness of the stock between 
the blanks. 
The position of the stop for a simple blanking die may be de- 








Machinery 



Fig. 41. Diagrams Illustrating how Location of Stop-pin may be 
Determined 

termined as follows: Draw outlines representing the two holes 
that are punched successively, so that they occupy the same 
relative positions as required for the holes in the stock; then 
draw a line parallel to the edge of the stock as at a - a and 
measure the distance along this line between corresponding 
points on the outline, thus obtaining dimension x. This di- 
mension equals the amount that the stock must be moved for 
each stroke of the press, and, therefore, the distance that the 
stop-pin should be located from that edge of the hole which is 



o() BLANKING DIE CONSTRUCTION 

to «oinc against the stop-pin. Assuming that the shaded area 
represents th<- hole in the blanking die and thai point y on the 
sto* k is to engage the slop, then the stop pin s should be located 
.1 distance x from this point, in the direction in which the stock 
is to be l<'( I i hrough • he •lu- 
lu case the stock is to be passed through (In- die twice, as 
indicated .it B, Fig. 1 1 . in order to cut ii more economically and 
withoUl making .1 multiple die, the openings which are punched 
successively musl be considered when locating the slop pin or 
those which occupy the same position relative to the edge of 
the stock, For instance, il a\yc v is to engage the stop pin, the 
latter should be located ;i distance x equal to the distance from 
edge y io die corresponding edge ol the next hole which is cul 
during this same passage oi the stock. The position ol the 
stop-pin relative to the hole m the stock, depends upon the 
shape ol the hole. Ii should be placed so as to engage whal 
eve] p. oi ol the edge will provide the best contacl point lor the 
slop pin, a straight p. iii ol the hole being selected in preference 
io .in irregulai section il convenient. Whenever possible, how 
ever, the point should he in such .1 position with relation to the 
hole that when the stock is pushed against it, the tendency will 
he io force the stock over towards the guide ship. When 
pun< h<"' are equipped with pilots the stop pin in the die should 
bo so lot. lied that when the pilots ente] the pierced holes they 
will tend to move the stock slightlv away from the stop pin. 
It the stork were crowded against the stop pin, a sheared die or 

.1 burred hole where the pilot enters would he the result 

Types of Die-bods 01 Bolsters. I bos are usually held in 
position on the bod ol a punch press by means o! a die bod or 

bolster, although large dies are often attached directly to the 
press bed 

the subject oi die beds or bolsters is one ol considerable un 
portance, and is deserving ol greatei attention than it often 
receives in the .hop or designing 100m. because many ol the 

troubles eneountered in (he use of press tools an- due to these 

parts being badly designed or poorly constructed. Main a fine 

die has been ruined beeause it has not been properly soeured in 



i>ik I'.kds oe r.oi.M v.\>:\ 



07 



the die bed and consequently has shifted while in operation; or 
because the holes in the die-bed through which the blanks or 
pun< hings are supposed to pass have nol been made large enough 
to allow them to pass through freely. A:, a consequence the 
blanks gel jammed in the die bed and pile up into the 'lie itself 
and are compressed by the pounding oi the punch, until the 
pun< li or die breaks from the strain. The |>iin< ipal fun< tions "I 
;i die bed are; first, thai oi supplying an adequate supporl for 
the die, and a holder to hold the die in its propel position to be 
engaged by the punch; and, second, to furnish a means "I al 
tachmenl to the press. Therefore the principal point, to be 




Wg. 4/. Form of \))<: ii'-.d i.ommonly ir;<:<) in fobbiflg SllOpfl 

considered in the design and construction oi a die bed are first, 
the method oi securing the die, and second, the method oi 
securing the die bed to the press, Due consideration, oi coui < , 
should also be given to proportion and strength. 

A die bed oi the type generally found in the jobbing shop is 
shown in Fig. 42. The dovetail method oi holding the die, 
with set-screws E to loci it in propel position, is employed, it 
i, fitted with a flange on each end with slots S to receive the 
clamping bolts which pass through the slots into the press 
bolster, [n the center is a rectangular cored hole to lei the 
pun< hings pa 1 - through. 'I hi . type oi die bed is < heap and con- 
venienl for use where teveral dies are to be u ted in one <\\<- bed. 
The dies can be easily slid into place and fastened by means oi 



9 8 



BLANKING DIE CONSTRUCTION 



the set-screws, and are easily removed when another die is to 
be used. The angle a of the dovetail should be from 75 to 80 
degrees. This die-bed has the following disadvantages: first, 
that the die is held into it by set-screws which always have a 
tendency to jar loose in punch press work, and, second, the 
cored hole C, being necessarily made large to accommodate 
various shapes of blanks, weakens the die-bed and lessens the 
support to each of the dies. It is always better, if possible, to 
have a separate die-bed for each die. 




Machinery 



Fig. 43. Die-bed adapted to Inclined Press 

In Fig. 43 is shown a die-bed for use on an inclined press. 
In this bolster the dovetail method of holding the die is used, 
but without the use of set-screws. The dovetailed opening to 
receive the die is slightly tapered and the die is driven into 
place with a copper mallet, and is then made doubly secure by 
the insertion of a dowel G which is driven through the die into 
the die-bed. The method of clamping this die-bed to the press 
bolster is different from that shown in Fig. 42, in that the bolt 



DIE-BEDS OR BOLSTERS 



99 



slot in one flange runs at right angles to that in the opposite 
flange. By having the slots in this position, the die-bed may 
be attached or removed without the necessity of taking out the 
bolts, thus not only saving a great deal of time and trouble in 
setting the tools, but also preventing the bolt holes from getting 
filled with scrap or dirt and the bolts from getting lost. This is 
an excellent die-bed for blanking and piercing work. Another 
common method of holding a die without the use of set-screws 



SS©G 




5S3-G— 



Machinery 



Fig. 44. Form of Die-bed adapted to General Use 

is to make the dovetail slot tapering and somewhat wider than 
the die, so that a taper key can be driven in lengthwise. 

An improved type of die-bed for general utility is shown in 
Fig. 44. In this bed the dovetail method of holding the die is 
used. In the illustration it will be noticed that there are four 
parallel pieces or gibs E placed along the sides of the die. The 
object of this construction is to provide for dies of various sizes. 
When a larger die is to be used one or more of these gibs may be 



IOO 



BLANKING DIE CONSTRUCTION 



taken out. This bolster, in addition to four bolt slots, has a 
flange B all around it so that it may be clamped in any position. 
The set-screws H which hold the die in place should be pro- 
vided with a lock-nut as shown at / to lessen the chances of 
jarring loose. The great advantage of having a flange all 
around the bolster will be apparent when it becomes necessary 
to swing the die-bed around enough to bring the bolt slots out 
of line with the tapped holes in the press bolster. In a case of 
this kind a die-bed with a flange all around it may be clamped 
by means of clamps as shown at D, using the tapped holes G 
located at different places in the press bolster. 



^J. 




Fig. 45. Die-bed of the Dovetailed Type, equipped with Side Set-screws 
and End-thrust Screws 

In Fig. 45 is shown another die-bed of the dovetail and side 
set-screw variety, but with the additional feature of end-thrust 
set-screws. This end-thrust arrangement is a novel feature. In 
order to obtain this additional means of holding the die securely, 
two square grooves B are cut in each end of the die-bed at right 
angles to the opening for the die. Into these grooves a plate C 
is fitted in which there is a set-screw in such a position as to 
come into contact with the end of the die. With one of these 
plates at each end, and the set-screws screwed tightly against 
the ends of the die, there is less likelihood of its shifting while in 
operation. When short dies for simple blanking or piercing are 
used, the end-thrust plates may be inserted in the inner grooves 



DIE-BEDS OR BOLSTERS 



IOI 



as shown in the illustration, whereas if it is desired to use a long 
die such as is used for progressive work where there is one or 
more piercing operations before the work reaches the blanking 
punch, the plates with the set-screws may be placed in the 
grooves further from the center, and thus allow for the increased 
length of die. When the set-screws are used in these outer 
grooves, the heads of the screws will come directly over the 
slots in the flanges where the clamping bolts should be placed; 
for this reason the bed should be provided with two extra slotted 
flanges, as shown in the illustration, to be used when necessary. 





















Op 




I'cll ilc! 
li ii h ii 




) 




Jgp 




" c 

KiSfiffii! 




?=K \' 

B (*§$)) 


C 
__C_ 


B ■ 
















1 iifflilii 




I 








M 1 Nil 












B 


B 




B , 


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Mo 


chinery 



Fig. 46. Die-bed for Sectional or Split Dies 

A die-bed for sectional forming or blanking dies or for split 
dies is shown in Fig. 46. This die-bed is provided with a square 
receptacle to receive the dies, and with two set-screws on each 
side to hold the dies in place. The square forming die shown is 
made in four sections B which are held tightly against each 
other by means of the set-screws C, and are held from working 
up by screws through the bottom of the die-bed — one in each 
section of the die. A square recess is cast in the die-bed so that 
when machining the die-bed it is only necessary to plane off the 
bottom and top of the flanges, mill the bottom of the recess, 
and drill and tap for the set-screws. The sides of the recess 
need not be machined as the dies have no bearing on them. 

A very simple type of die-bed for bending and forming dies 
is shown in Fig. 47. It is simply a vise similar in some respects 
to a milling vise, but having two set-screws to take the place of 



102 



BLANKING DIE CONSTRUCTION 



the movable jaw. The die is simply set in the bed and clamped 
against the solid jaw by means of the set-screws. This type of 
bolster is intended for use only on dies that do not require a 
" push up," or " knockout," and when the bending or forming 
operations are done on a solid surface. In order to obtain the 
best results from this die-bed, the complete outfit of punch-holder, 
punch, and die of the type shown in the sketch should be used. 
The punch and die are kept in alignment when in operation by 
the two guide pins E which are secured in the punch and which 




Fig. 47. Simple Form of Die-holder adapted to Bending Dies 

enter the die at every stroke of the press, making it practically 
impossible for the tools to shift while in operation. If it be de- 
sired to change the tools it is not necessary to disturb the punch- 
holder or die-bed. They may be left in the press, and, by simply 
loosening the set-screws in the die-bed and punch-holder, the 
punch and die, held together by the guide pins, may be taken 
out and set aside and another set slipped into their places. 

A bolster for combination dies for round drawing work is 
shown in Fig. 48. This bolster requires but little explanation. 
It is circular in shape with two steps or extensions, two bolt 
slots, and a flange all around it to allow it to be clamped at any 
convenient place. When the combination dies are turned in 
the lathe, the bottom die is counterbored to be a driving fit on 
the extension G, and is held down by screws that pass through 
the bed at E into the die. 



DIE-BEDS OR BOLSTERS 



103 



Die-beds are commonly made of cast iron, cast steel, or 
machined steel. Of late years there has been a tendency among 
large concerns to have all their die-beds for the power press 
made from semi-steel castings, or of machine steel for certain 
classes of heavy work, instead of from cast iron as heretofore. 
This is done because a cast-iron die-bed that is used day after 
day for holding dies for cutting heavy metal will not stand up 
during long and hard usage as it should. Past experience has 
proved that gray iron die-beds in time become out of square; 
then, again, they sometimes crack. With the semi-steel, or the 




Fig. 48. Die-bed or Bolster for Combination Dies Designed for Round 
Drawing Operations 

soft steel die-bed, this does not happen. It has been found that 
semi-steel and machine steel die-beds pay for themselves many 
times over. 

Examples of Blanking and Piercing Dies. — Some interesting 
examples of die work taken from the diemaking department 
of the Taft-Peirce Manufacturing Co. are shown in Fig. 49. 
While the dies illustrated are used to produce comparatively 
plain parts, there are some points in their construction which 
may be of interest and value, particularly to those not ex- 
perienced in the art of diemaking. The die shown to the left 



104 



BLANKING DIE CONSTRUCTION 




EXAMPLES OF BLANKING DIES 



I°5 



is for producing the part illustrated at A in Fig. 50, which also 
shows the successive piercing, bending, and blanking operations. 
The stock is fed through the die in the direction indicated by 
the arrow. On the first stroke the piercing operation at a is 
performed by a punch of corresponding shape. On the next 
stroke a bending punch turns over the part b h making a right- 
angle bend, and, finally, the finished piece is blanked out. Of 




Fig. 50. Blanked Parts and Scrap, Illustrating Successive Operations 

course these operations all take place simultaneously, except 
when the stock is first being started, so that a finished piece is 
blanked out at each stroke. 

One of the interesting features of this die is the method of 
stopping the stock as it is fed forward. After the bending oper- 
ation, which takes place at b% on the die, the bent end b\ (Fig. 50), 
which projects downward below the surface of the die, is fed 
forward through channel d until it comes against the end di 



106 BLANKING DIE CONSTRUCTION 

which forms a positive stop. By this simple method, the stock 
is located for the pilot-pins which accurately position it for the 
blanking operation. By means of the spring pressure-pad P, the 
stock is held firmly against the die, so that it will not be buckled 
by the bending operation. When the stock is first being started 
through the die, stops S, which may be moved in or out as re- 
quired, are used for locating the stock for the first and second 
operations. 

The die shown in the center of Fig. 49 is for piercing and 
blanking the pawl illustrated at B in Fig. 50, which also shows 
a sample of the scrap. As the V-shaped projection h on one end 
of this pawl and the straight surface i had to have a smooth 
finish, a shaving operation on these surfaces was required. This 
operation is not performed in a shaving die after blanking, as 
would be necessary if the entire contour of the part had to be 
finished, but it is done in the blanking die by removing a certain 
amount of metal adjacent to these surfaces, as atj and k, during 
the piercing operation. The result is that when the pawl is 
blanked, the edges opposite the openings j and k are subjected 
to a shaving action which leaves a smooth surface that is en- 
tirely free from the roughness found on the other edges where 
the stock is sheared from the solid. The narrow shavings, which 
are removed from the surfaces to be finished, remain attached 
to the scrap in this particular instance, as the illustration shows. 
It will be seen that when this method of securing a finished 
edge is employed, the stock must be accurately located, as the 
removal of a shaving that is too thick would roughen the edge. 
In the die illustrated, the stock is located by the two pilot-pins 
on the punch, one entering the hole n, Fig. 50, and the other a 
hole pierced simply to give a two-point location, thus insuring 
accuracy. In practice it has been found that a shaving equal 
to 10 per cent of the stock thickness is about right for mild 
steel. 

This die is equipped with an automatic stop Si which is oper- 
ated by a projecting screw on the punch in the usual way. 
The hole in this stop for the pivot on which it swivels is tapered 
toward the center from both sides, thus giving it a movement 



EXAMPLES OF BLANKING DIES 



10: 



horizontally as well as vertically. With the stop mounted in 
this way, slight adjustments, to compensate for any error there 
might be in the location of the stop with reference to the pilots 
in the punch, can easily be made when the die is being tried out, 
by simply turning the screw s until the stop is properly positioned. 
The function of the stop is, of course, to locate the stock ap- 
proximately, and its flexibility prevents the pilots from being 
subjected to excessive strains. The horizontal adjustment has 













o°. 









PLAN OF DIE 



_ 






I:- 1 



~ 



f7 



L 



Machinery 



Fig. 51. Follow or Progressive Die equipped with Trimming Punch for 
Trimming Edge of Sheet Stock 

an additional advantage in that the stop does not have to be 
located so accurately when this adjustment is provided. 

Another punch and die of the piercing, shaving, and blanking 
type is shown to the right in Fig. 49. In this case the work C 
in Fig. 50 had to be finished in three places, as shown by the 
perforations at p, q, and r. The stock is pierced for shaving by 
three punches while two other punches pierce the holes t\ and k, 
Fig. 50. The hole h is merely for locating purposes, there being 
two pilots which give a two-point location. This die is also 



108 BLANKING DIE CONSTRUCTION 

equipped with an automatic stop similar to the one previously 
described, and it has small hand stops 5 2 which are also common 
to the designs previously referred to. 

Follow Die Equipped with Trimming Punch. — When stock is 
purchased of the proper width for blanking two rows of parts, 
one edge is placed against the guide of the die and the stock is 
fed through, after which it is turned over and fed through with 
the opposite edge against the guide, but if the stock is purchased 
in sheets, it is necessary to trim the edges every time a row is 
punched, with the exception of the two outside rows. If no 
power shears are convenient to the press, this may prove to be 
a more costly operation than punching, and even though a shear 
may be located near the press, the operation adds considerably 
to the cost of the product. To avoid this trouble and expense, 
a trimming punch A is sometimes added, as illustrated in Fig. 51, 
which shows a die of the follow type. The purpose of this 
punch is to remove the scrap between the openings in the sheet 
and also to trim the edge of the sheet straight so that it may be 
used for guiding the stock when blanking out the next row. 
When a trimming punch is employed, a stop of the type shown 
at 5 in the illustration is used. The end of the scrap strikes 
this stop, thus locating the stock; when the punch descends, 
the scrap formed by the blanking operation is cut away, thus 
trimming the edge straight. When making dies of this class, it 
is necessary to have the blanking punch longer than the others 
in order that the locating or pilot-pins on the end can engage 
the holes in the stock before the other punches begin to cut. 
It is also advisable to place the stop so that the stock will go a 
little farther (say, 0.010 inch) than its correct location; then, 
when the pilot-pins engage the pierced holes they will draw the 
stock back to the proper position, whereas, if the diemaker at- 
tempted to set the stop so as to locate the stock exactly, any 
dirt or other foreign substance between the end of the scrap and 
the stop would cause trouble. 



CHAPTER III 
DRAWING AND FORMING DIES 

Notwithstanding that drawing dies are extensively used, there 
has been a lack of definite information pertaining to fundamental 
principles and rules governing the drawing of sheet metal, 
which is doubtless due to the fact that the exact method of de- 
signing and constructing a drawing die depends, to such a large 
extent, upon the nature of the drawing operation. Moreover, 
it is doubtful if any branch of diemaking requires more experience 
than that which has to do with the drawing of sheet-metal 
parts. The following information pertaining to drawing die 
construction and design pertains to practical problems such as 
are frequently encountered in actual practice. 

When a drawing die is to be made for producing a cup or shell, 
it is necessary to determine what form or type of die will give 
the best results, what diameter of blank would be required to 
produce a shell of the required form and depth, and whether 
more than one drawing operation is necessary. These questions, 
as well as other important points relating to the drawing of 
sheet metals, will be considered in this chapter. 

Selecting Type of Drawing Die. — The type of die to use 
depends primarily upon the shape of the drawn part and the 
nature of the drawing operation, although the quantity of parts 
required may also affect the design of the die. If comparatively 
shallow cups or shells, such as can or box covers, were required 
in quantity, a combination die and a single-action press would 
ordinarily be used, whereas, if the cups were quite deep or 
simply the first of a series of operations, a double-action blank- 
ing and drawing die would usually be employed. On the other 
hand, if comparatively few drawn parts were needed, it might 
be advisable to do the work in two operations by first cutting 
out the blank in a plain blanking die and then drawing it in 

109 



HO DRAWING DIES 

another die of the simple push-through type. Such a die, how- 
ever, should only be used for metal having a thickness of at 
least j 1 q inch and for producing shallow cups. 

The principal reason why drawing dies of the combination 
type having pressure-pads are only adapted to the drawing of 
shallow cups, is that the pressure of the blank-holder on the 
stock gradually increases as the cup is drawn, owing to the 
increased compression of the rubber attachment; consequently, 
the stress upon the metal being drawn is increased rapidly as 
the drawing punch descends, because the stress due to the 
drawing operation is unduly increased by an excessive pressure 
on the outer part of the blank. When the pressure on the 
blank is practically uniform, as in the case of a double-action die, 
a somewhat greater depth can be obtained in one draw, assum- 
ing that the same material is used in each case and that other 
conditions are equal. To avoid this increase of pressure, some 
combination dies are equipped with a compensating attach- 
ment for obtaining a more constant pressure between the draw- 
ing punch and blank-holder. 

When designing drawing dies the number of drawing oper- 
ations necessary must also be considered. If a deep shell is to 
be drawn and a double-action drawing die is used to form the 
cup, redrawing dies will be necessary to gradually lengthen and 
reduce the diameter of this cup, in order to form the shell. 
There are two general types of redrawing dies as already explained 
in Chapter I. In the simplest type the cup is redrawn by 
simply being pushed through a smaller die in a single-action 
press and, if necessary, the shell thus formed is further reduced 
and elongated by pushing it through a series of similar dies. 
(The reductions in diameter that are practicable for each draw 
will be referred to later.) This simple form of redrawing die is 
used for small parts, especially when the metal is comparatively 
thick and does not wrinkle, to any great extent, while being 
drawn. For large thin work, redrawing dies having inside 
blank-holders are commonly used. The blank-holder prevents 
the formation of body wrinkles as the work is being pushed 
through a smaller opening and this support to the body also al- 



DRAWING DIE DIAMETERS III 

lows a greater reduction of metal to be obtained in one drawing 
operation. Redrawing dies having blank-holders should be 
used when work is large and especially if the stock is thin in 
proportion to the diameter. 

Depth of the First Drawing Operation. — When a shell or cup 
is to be drawn from a flat blank, the diemaker or designer must 
decide how many drawing operations will be required. Shallow 
cups, can covers, etc., can be drawn in one operation, but, 
when a comparatively deep shell is required, two or more oper- 
ations are necessary, the number depending upon the quality 
and kind of metal, its thickness, the slant or angle of the dies. 
the amount that the stock is thinned or ironed in drawing and 
the thickness of the metal in proportion to the diameter of the 
work. As a general rule, a plain cylindrical shell should not be 
drawn to a depth which is greater than its diameter, and some 
diemakers contend that the depth should not exceed from one- 
half to two-thirds the diameter. When an attempt is made to 
draw a blank to a great depth, so much pressure is required 
to contract the flat stock into a cylindrical shape that the tensile 
strength of the metal is exceeded. If the shell is to have a 
flange at the top, it will not be practicable to draw as deeply as 
previously stated unless the metal is extra good, because the 
stock is subjected to a higher tensile stress, owing to the larger 
blank which is necessary for forming the flange. 

Diameter of First Drawing Die. — When detennining the 
diameter of the hrst drawing die (often called the " cupping die"), 
it is well to be conservative and not attempt to draw too deeply 
in one operation in order to reduce the succeeding operations to 
a minimum, because broken shells may result. Ordinarily, it is 
practicable to draw sheet steel of any thickness up to f inch, so 
that the diameter of the hrst cup equals about 0.6 of the blank 
diameter, and under favorable conditions the diameter of the 
first cup may equal from 0.4 to 0.5 the blank diameter. A good 
general rule to follow is to make the diameter of the first draw- 
ing die equal to the blank diameter divided by 1.8 or, 

tv , ,. blank diameter 

Diameter oi die = 

1.8 



112 DRAWING DIES 

Diameter Reductions of Drawn Shells. — When a compara- 
tively deep shell is to be drawn, the cup which is formed from 
the flat blank in the first drawing die is redrawn one or more 
times, thus decreasing its diameter and . increasing its length. 
The amount that the diameter of a plain shell can be reduced 
in these successive steps or redrawing operations, depends upon 
the quality and kind of metal, its susceptibility to drawing, 
whether or not the die is equipped with a blank-holder, the 
thickness of the stock and the amount that the stock is "ironed'' 
or thinned while being drawn. A general idea of the reductions 
that are practicable for various thicknesses of metal may be 
obtained from the following figures. 

Approximate thickness of sheet steel, 

inrh - 1 - A - 3 - A - 5 - 

1I1Ln 16 8 16 4 16 

Possible reduction in diameter for each 

succeeding step, per cent 20 15 12 10 8 

For example, if a shell made of ^g-inch stock is 3 inches in 
diameter after the first draw, it can be reduced 20 per cent on 
the next draw, and so on until the required diameter is obtained. 
These figures are based upon the assumption that the shell is 
annealed after the first drawing operation, and at least between 
every two of the following operations. Necking operations — 
that is, the drawing out of a short portion of the lower part of 
the cup into a long neck — may be done without such frequent 
annealings. In double-action presses, where the inside of the 
cup is supported by a bushing during drawing, the reductions 
possible may be increased to 30, 24, 18, 15, and 12 per cent, 
respectively. (The latter figures may also be used for brass 
in single-action presses.) 

The foregoing figures represent conservative practice and it is 
often possible to make greater reductions than are indicated by 
these figures, especially when using a good drawing metal. 
Taper shells require smaller reductions than cylindrical shells, 
because the metal tends to wrinkle if the shell to be drawn is 
much larger than the punch. The amount that the stock is 
"ironed" or thinned out while being drawn must also be con- 



DRAWING DIE DIAMETERS 113 

sidered, because a reduction in gage or thickness means greater 
pressure of the punch against the bottom of the shell; hence 
the amount that the shell diameter is reduced for each drawing 
operation must be lessened when much ironing is necessary. 

Formulas for Drawing Die Diameters. — In order to determine 
more definitely the diameters that are practicable for drawing 
dies, several hundred tests were made on various thicknesses of 
steel stock, using different die and blank diameters. These tests 

showed that the ratio of — — - — for the same thickness 

blank diameter 

of metal is not constant (assuming that the same quality of 

drawn work is obtained in each case), but that an increase in 

blank diameter means an increase in ratio; in other words, the 

diameter of the first drawing die should be proportionately 

larger as the diameter of the blank increases. The following 

formulas for determining die diameters are the result of these 

tests and apply to drawing dies intended for soft steel or tinplate: 

For first-operation dies: 

d- XXD ■ 

100 — 0.635 D 
For redrawing dies: 

, XiXd , , XiXdi 

dl = 7TTa> d2 = 2 — T> etc - 

100 — 0.035 a 100 — 0.635 di 

In these formulas, 

D = the calculated blank diameter; 
d = diameter of the first-operation drawing die; 
di = diameter for first redrawing die; 
d\ = diameter of following redrawing die; 
X and Xi = factors which depend upon the thickness of the 
metal to be drawn. 

These factors X and Xi for different thicknesses of stock are 
given in the accompanying table " Minimum and Maximum 
Values for Die Diameter Formulas." The numerical values 
of these factors were found by making several hundred trial 
draws, using different blank and die diameters and different 
thicknesses of stock. It should be mentioned that the results 



ii4 



DRAWING DIES 



are correct only for dies used in double-action presses where the 
blank-holder pressure is constant and, in the case of redrawing 
dies, inside blank-holders having 45-degree drawing edges are 
employed. 

Minimum and Maximum Values for Die Diameter Formulas 



Metal Thickness, 


First-operation Die 
X 


All Redrawing Dies 
Xi 


Inch 


Minimum Maximum 


Minimum Maximum 


0.016 to 0.018 


6r 68 


74 81 


O.02 


58 65 


73 80 


0.022 to 0.024 


56 63 


72 80 


O.028 


54 60 


71 7Q 


O.03 


50 56 


70.5 77 


O.06 


47 53 


70 75 


O. 12 


5i 


65 



Formation of Wrinkles in Drawing. — The reason why 
wrinkles tend to form when drawing sheet stock will be more 
apparent if we consider the action of the metal as it is forced 
through the die. When a flat blank is drawn either in a com- 
bination or double-action die, the outer part is subjected to 
pressure by the blank-holder; consequently, no wrinkles can 
form if the die is properly constructed, and all the movement 
must be radially inward (provided a circular or cylindrical shape 
is being drawn), but when the metal passes from under the 
blank-holder and over the edge of the die, it is no longer con- 
fined and, as it is being drawn into a smaller circumference, the 
natural tendency is to wrinkle. These are sometimes known as 
"body wrinkles" to distinguish them from the " flange wrinkles" 
which result when there is insufficient pressure between the 
blank-holder and die. 

As the stiffness of sheet metals increases approximately as 
the square of the thickness, thicker metals also offer more re- 
sistance to a buckling or wrinkling action when being reduced 
to a smaller circumference, than comparatively thin stock. 
For this reason, stock thicker than ^ or -fa inch is often drawn 
in plain push-through dies that are not provided with a blank- 
holder, and there is little or no trouble due to wrinkling. When 



SHAPES OF DRAWING EDGES 115 

drawing very thin metal, wrinkles are difficult to avoid, es- 
pecially if the diameter of the work is quite large. More trouble 
is experienced from wrinkles on taper than on cylindrical parts. 
The reason is that when the point of the taper drawing punch 
engages the stock, there is a comparatively large annular zone 
of metal between the end of the punch and the edge of the 
drawing die, and, as the stock is forced into this zone, the 
natural tendency is to buckle. When drawing tapering cake 
pans or other parts which have scalloped sides, the wavy for- 
mation naturally eliminates trouble from wrinkling; in fact, 
such parts can be drawn without a blank-holder in a single- 
action press. 

Drawing Edges for First-operation Dies. - - The shapes of the 
edges of drawing dies, for cylindrical work, vary somewhat even 
for dies of the same class. The shape depends, to some extent, 
upon the nature of the drawing operation, but the different 
forms of drawing edges in use, even for the same general class 
of work, are due in part to the difference of opinion among die- 
makers and also to a lack of specific information on this im- 
portant point. When first-operation dies and those used for 
drawing cups from flat blanks are not equipped with a blank- 
holder, it has been found good practice to bevel the upper part 
of the die to an angle of 60 degrees, as shown at A , Fig. 1 . The 
advantage of this steep beveled surface is that it tends to pre- 
vent wrinkling, although a die of this type or one not having 
a blank-holder should not be used on stock thinner than, say, 
":i2 or iV mcn - The amount of bevel for a die of this class 
should be such that the flat blank will have a bearing w of about 
I inch on each side of the die opening. Some diemakers seldom 
make this width less than j$ inch or greater than \ inch, whereas, 
others use a bearing varying from \ to -fy inch, depending upon 
the size of the die and the thickness of the stock. 

The upper and lower edges of the beveled surface are rounded, 
the radius depending somewhat upon the thickness of the stock. 
It has been found good practice to vary this radius from about 
I inch on a die for No. 16 gage stock to about \ inch for dies in- 
tended for stock of, say, j-inch thickness. The seat or nest for 



n6 



DRAWING DIES 



locating the flat blank concentric with the die opening is formed 
either by counterboring down into the die or by attaching a 
locating plate to the top of the die. Some first-operation dies 
that are not equipped with blank-holders have round edges in- 
stead of the bevel form. The latter, however, is considered 
preferable as it will enable deeper cups to be drawn and there is 
less tendency of the stock to wrinkle. 

Most first-operation drawing dies are equipped with blank- 




Fig, i. Shapes of Drawing Surfaces of First-operation Dies and 
Redrawing Dies 

holders and such dies have rounded drawing edges, as indi- 
cated at B, Fig. i. When making a die of this form, the radius 
of the drawing edge is very important. Evidently, if this edge 
were left square it would tend to cut the metal and the latter 
would not flow over it readily, if at all; consequently, the stress 
upon the metal might exceed its tensile strength and the shell 
would be ruptured. By using a curved drawing surface, how- 
ever, this difficulty is overcome because the curved edge offers 
less resistance to the inward flow of the metal. The effective- 



SHAPES OF DRAWING EDGES 117 

ness of a drawing die may depend upon the radius of the draw- 
ing edge. For instance, if the radius r is too large, the fiat part 
of the blank will receive insufficient support from the blank- 
holder and, as the result, the metal tends to wrinkle after the 
edge of the blank reaches the curved surface and the metal is 
no longer supported. If wrinkles form, they may be straightened 
out by the pressure of the drawing punch, but this operation is 
liable to develop flaws and minute cracks in the metal unless 
the latter is very ductile. The radius r depends upon the 
thickness of the stock and, to some extent, upon the nature of 
the drawing operation. A general rule that is used by some 
diemakers is to give the die a radius equal to from six to ten 
times the thickness of the stock. 

When a part is drawn in one operation, or if the die is for a 
final operation, and it is especially desirable to secure an even 
top edge for the cup or shell being drawn, the radius of the 
drawing edge should be reduced as much as possible. When 
the outer edge of the blank after leaving the blank-holder be- 
gins to pass over the rounded part of the die, it is no longer sup- 
ported by the blank-holder, and, consequently, is free to follow 
the natural tendency to wrinkle. Therefore, when it is essen- 
tial to secure an even top edge, the radius should be reduced to 
a minimum. If this radius is made too small, however, there is 
danger of stretching and straining the metal excessively or even 
tearing it, because of the increased friction resulting from 
drawing the metal over too sharp an edge. On the other hand, 
if the radius is too large, the blank lacks the support necessary 
to prevent wrinkling, as previously mentioned. 

For thin stock, this radius may be very small and, in extreme 
cases, the drawing edge is almost square, the advantage being 
that thin shallow cups drawn in such a die will have even top 
edges which, in many cases, do not require trimming. When 
the stock is thicker than about -fy inch, the radius can be made 
fairly large without trouble from wrinkling, because the heavier 
stock "clings" better to the drawing surface of the die. As a 
rule, cupping or first-operation dies for drawing cups or shells 
from flat blanks should always be equipped with blank-holders 



Il8 DRAWING DIES 

for stock thinner than ^ or ^ inch, although the diameter re- 
duction that is necessary must, of course, be taken into con- 
sideration. The length x of the drawing surface of the die is 
usually made about § or \ inch. If this surface is too long, it 
may increase the frictional resistance between the die and shell 
wall to such an extent that excessive stretching and straining of 
the metal occurs. 

When using a plain push-through type of die, such as is shown 
at A, the relation between the blank and cup diameters is about 
the same as when using a double-action die. A cup drawn in 
a push-through die, however, will have a much more uneven 
edge along the top than if drawn in a die equipped with a blank- 
holder; consequently, if several redrawing operations were re- 
quired, it might be necessary to trim the edge of the shell after 
the third or fourth draw in order to facilitate stripping the 
shell. It is the practice of the Worcester Pressed Steel Co. 
not to use plain push-through dies for cups having a depth ex- 
ceeding \ inch, except when the stock is thicker than about 
f inch. When drawing a comparatively deep cup from stock 
varying, say, from -£$ to \ inch in thickness, without using a 
blank-holder, the metal tends to thicken or gather in folds 
toward the top and has to be ironed out, which may cause undue 
strain on the shell. The minimum stock thickness, when using 
a plain push-through die, depends somewhat upon the shell 
diameter. 

Drawing Edges for Redrawing Dies. — The shapes of the 
drawing edges for two commonly used types of redrawing dies, 
or those employed for reducing the diameters of cups or shells, 
are shown at C and D, Fig. i. Sketch C shows a die which is 
similar to the one illustrated at A in that it has a 6o-degree 
beveled drawing surface. The upper part of the die, however, 
has a deeper seat or nest for locating the cup to be redrawn. 
This simple push-through type of die is used ordinarily for re- 
drawing stock which is at least ^g inch thick. For thinner metal 
an inside blank-holder is commonly employed, a die of the type 
shown at D being used. The advantages of this latter type of 
die for redrawing are that greater diameter reductions can be ob- 



SHAPES OF DRAWING EDGES 1 19 

tained and there is less tendency for the stock to wrinkle, because 
the blank-holder supports the metal while it is being drawn from 
the outer circumference to the smaller one corresponding to the 
size of the die. As will be seen, the drawing surface is beveled 
to an angle a and is joined to the outer seat and inner drawing 
surface of the die by rounded corners. The radii of these 
corners is generally made quite small, often being | inch or less. 
Some diemakers, however, increase the radii of these corners 
considerably as compared with the figure just given; in fact, 
in some cases the corners are rounded to such an extent that the 
straight beveled surface is entirely eliminated and the drawing 
surface of the die is simply a reverse curve. It is generally con- 
ceded, however, that the beveled edge is preferable. In the 
first place, it is claimed that the metal flows more readily over 
the beveled edge and there is another advantage in that the 
beveled surface forms a better seat for the shell, provided the end 
of the punch in the preceding die is given a corresponding taper. 

The angle a of this beveled seat is generally varied according 
to the thickness of the metal to be drawn and ranges from 30 
to 45 degrees, the thicker the metal the greater the angle. The 
following data taken from practice, show in a general way, the 
relation between the angle and stock thickness. For metal 
thinner than g 1 ^ inch, angle a is made 30 degrees; for metal 
varying from g 1 ^ to jg inch, angle a is made 40 degrees, and for 
stock iq inch and thicker, angle a is made 45 degrees. 

Clearance for First-operation Drawing Die. — When a flat 
blank is changed into a cylindrical shape in the drawing die, the 
natural tendency of the annular part of the blank, which is com- 
pressed into a cylindrical shape, is to buckle and wrinkle, because 
it is changed from a flat to a circular form. Wrinkling is pre- 
vented, however, because there is not sufficient room between 
the die and punch to permit the formation of wrinkles, but the 
cylindrical wall of a cup which is drawn from a flat blank tends 
to increase in thickness during the drawing process, because the 
metal which is confined between the punch and die is com- 
pressed or upset circumferentially. Therefore, a first-operation 
drawing die, or "cupping die," as it is often called, is sometimes 



120 DRAWING DIES 

given a slight clearance to allow for this increase in thickness; 
that is, instead of making the space between the punch and die 
equal to the thickness of the stock, the diameter of the die is 
made equal to the diameter of the punch plus from 2.2 to 2.4 
times the stock thickness. For some classes of work additional 
clearance is allowed to reduce the friction between the stock and 
the surfaces of the punch and die, the allowance being determined 
by the following rule: The diameter of the die should equal the 
diameter of the punch plus from 2.6 to 3.2 times the thickness ' 
of the stock. 

Insufficient clearance and the resulting increase of friction 
and wear affect the life of the tools and cause an unnecessary 
increase in the operating power. On the other hand, if too 
much clearance is given, the drawn shell will be somewhat 
conical in shape and full of wrinkles which cannot readily be 
ironed out by the redrawing dies. It is the practice of some die- 
makers to allow a slight clearance and then bevel the drawing 
surface of the die inward towards the bottom to iron out the 
metal and maintain the original thickness of the stock. If the 
die is used for a comparatively rough drawing operation, this 
ironing is not necessary and the stock is allowed to thicken. 

Ironing or Thinning the Stock. — When a cylindrical shell or 
similar part is to be drawn and a dead smooth finished surface 
is required, it is necessary to use stock that is one or two gage 
numbers heavier than the thickness of the finished shell to 
allow for the thinning or ironing out of the metal. For instance, 
if the wall of a shell is to be, say, 0.025 mcn thick when drawn, 
the stock should be of No. 23 (0.0281 inch) or No. 22 (0.0313 
inch) U. S. standard gage, so that it can be reduced in thickness 
while being drawn. Evidently, in order to produce this iron- 
ing effect, the space between the punch and die must be some- 
what less than the thickness of the stock; that is, the diameter 
of the punch should be greater than the dimension obtained by 
subtracting twice the thickness of the stock from the die 
diameter. 

The extent to which shells are ironed or thinned in one draw- 
ing operation varies somewhat with the thickness and kind of 



IRONING THE STOCK 121 

metal and also its qualities as to hardness and ductility. When 
the stock is ironed simply to secure a smooth surface and ac- 
curacy as to diameter, about 0.004 i ncn would ordinarily be 
allowed for No. 16 gage steel stock. In general, when ironing 
is required, the diameter of the punch should equal the diameter 
of the die minus twice the thickness of the stock plus from 
0.004 to 0.008 inch. For the final drawing operation, when an 
extra fine finish is required, the allowances should not be over 
0.001 inch on a side; that is, the diameter of the punch should 
equal the diameter of the die minus twice the thickness of the 
stock plus 0.002 inch. In many cases, the dies are so made that 
there is no ironing of the shell until the last drawing operation 
and then the stock is thinned from 0.001 to 0.003 i ncn , but this 
ironing is not done unless necessary. To reduce the thickness 
of the metal more than the amount specified, the shell should 
first be drawn to its finished inside diameter and then ironed 
by separate operations. When thinning the walls of the shell 
by ironing, it is advisable to run the press slower than for ordinary 
drawing. 

While the foregoing figures apply to ordinary conditions and 
may not be an accurate guide in every case, they will serve to 
give a general idea of what is considered good practice. As 
previously mentioned, when the stock is to be ironed, this must 
be considered when determining the number of drawing oper- 
ations, because ironing adds considerably to the pressure of the 
punch against the bottom of the shell. Therefore, the diameter 
reduction for each draw must be less when the metal has to be 
ironed out. It may be necessary to reduce the diameter re- 
ductions one-half of what would be practicable when drawing 
without ironing. 

Finding the Blank Diameter. — Before making a blanking or 
drawing die, it is necessary to determine how large the flat blank 
must be in order to produce a shell or cup of the required form. 
Until the blank diameter is known, obviously that part of the 
die which cuts out the blank cannot be made. If the stock did 
not stretch while being drawn or was not "ironed out" and 
made thinner, the diameter of the blank could be determined 



122 



DRAWING DIES 



quite accurately by calculating the area of the finished article 
and then making the blank the corresponding area. In some 
cases, there is not much ironing and stretching, as, for example, 
when the part is drawn or formed to shape in one operation, and 
then the area method of calculating the blank diameter gives 
quite accurate results, but if the metal is to be made thinner as 
it is drawn to shape, the blank should, of course, be proportion- 
ately smaller in diameter. The kind of metal to be drawn, that 
is, whether steel, brass, copper, aluminum, etc., and whether it 
is hard or soft, also affects the size of the blank to some extent. 



r-s 
















I ', 








w 


16 












' L T 






< — 






i, 

2 

i 

i 












i 

i_ 








Machinery 



Fig. 2. Flanged Cup and Flat Circular Blank of Corresponding Area 

Owing to the uncertainty of obtaining the right blank diam- 
eter by calculation, a common method of procedure, especially 
when constructing drawing dies for parts requiring more than 
one or two drawing operations, is to make the drawing part of 
the die first. The actual blank diameter can then be determined 
by repeated trials, after which the blanking part of the die may 
be finished. One method is to get a trial blank as near to size 
as can be estimated. The outline of this blank is then scribed 
on a flat sheet, after which the blank is drawn. If the finished 
shell shows that the blank is not of the right diameter, a new 
trial blank is cut, either larger or smaller than the size indicated 
by the line previously scribed, this line serving as a guide. If 
a model or sample shell is available, the blank diameter can also 
be determined as follows: First cut a blank somewhat large and 
from the same material used for making the model cup, then 



BLANK DIAMETERS 1 23 

reduce the size of the blank until its weight equals the weight of 
the model. 

Calculating Blank Diameters. — A simple method of deter- 
mining the approximate blank diameter is by calculating the area 
of the drawn part and then making the blank the corresponding 
area. To illustrate, suppose the diameter of the blank for the 
flanged cup shown in Fig. 2 is required. The area of the bottom, 
which is 3 inches in diameter, equals 7.06 square inches. The 
area of the side equals 2 X 31V X 3.1416 = !9- 2 4 square inches. 
The area of the flange equals the area of a 4-inch circle minus 
the area of a 3-inch circle, or 12.56 - 7.06 = 5.5 square inches. 
The total area equals 7.06 + 19.24 + 5.5 = 31.80. The diam- 
eter of a circle having an area of 31.80 = 6f inches, nearly. 
When drawing a trial blank, it is the practice of some diemakers 
to cut the blanks somewhat smaller than the estimated size and 
then increase the diameter as may be required. When begin- 
ning with blanks that are oversize, the shell is liable to break 
owing to the excessive stress on the metal. From the foregoing, 
it will be understood that the blank diameter can only be de- 
termined approximately, because some metals stretch more 
than others and the pressure of the blank-holder as well as the 
radius or shape of the drawing punch and die, and the amount 
that the metal is ironed out, all enter into the problem and 
affect the result. Incidentally, the pressure of the blank-holder 
should be just enough to prevent formation of wrinkles as the 
stock is drawn radially inward, and this pressure should be 
as uniform as possible around all sides. 

Blank Diameter Rule for Plain Shells. — The blank diameter 
for a plain cylindrical shell having sharp corners can be de- 
termined approximately by the following rule. Multiply the 
diameter of the finished shell by the height; then multiply the 
product by 4 and add the result to the square of the finished 
shell diameter. The square root of the sum thus obtained equals 
the blank diameter. 

Formulas for Blank Diameters. — The diameters of blanks 
for plain cylindrical shells can be calculated by the following 
formula which corresponds to the rule given in the preceding 



124 DRAWING DIES 

paragraph. This formula gives a close approximation for thin 
stock and is one that has been extensively used: 



D = Vd 2 + 4 dh (i) 

in which D = diameter of flat blank; d = diameter of finished 
shell; // = height of finished shell. The blank diameters given 
in the accompanying table are based on this formula and are 
for sharp-cornered shells. The application of the formula is 
illustrated by the following example: 

If the diameter of a finished shell is to be 1.5 inch, and the 
height, 2 inches, the trial diameter of the blank would be found 
as follows: 



D = V1.5 2 + 4X1.5X2- V14.25 = 3.78 inches. 

For a round-cornered cup, the following formula, in which r 
equals the radius of the corner, will give fairly accurate diam- 
eters, provided the radius does not exceed, say, | the height of 
the shell: 

D = Vd 2 + 4 dh - r. (2) 

These formulas are based on the assumption that the thick- 
ness of the drawn shell is the same as the original thickness of 
the stock, and that the blank is so proportioned that its area 
will equal the area of the drawn shell. This method of calcu- 
lating the blank diameter is quite accurate for thin material, 
when there is only a slight reduction in the thickness of the 
metal incident to drawing; but when heavy stock is drawn and 
the thickness of the finished shell is much less than the original 
thickness of the stock, the blank diameter obtained from Formu- 
las (1) and (2) will be too large, because when the stock is drawn 
thinner, there is an increase in area. When an appreciable re- 
duction in thickness is to be made, the blank diameter can be 
obtained by first determining the "mean height" of the drawn 
shell by the following formula. This formula is only approxi- 
mately correct, but will give results sufficiently accurate for most 
work: 

*-* ( 3 ) 



BLANK DIAMETERS 



125 






a 
•a 

o 
»-l 

a, 

a. 
< 



Height of Shells 


>o 


OOMOCNOOMMON^tOOOMMOOOOCio-'tON'tOCCl 
^JiocoO^O m N «\0 m 10O -*t00 in 10 On COM3 O fO^ O ^t 


CN tfj^f U1l^v0>0 N NOO 00 On On On O O O M H CN <N CN coro 




v> 


H tfl O OOM N "3-00 H CO "3" CO <N OnO IN 00 COOO <N LO On 
"t "t CI O^OO IOO >0 On ^"00 CN O O tONH "tOO M IO00 M 


CN CO "t "t LOO O N N NOO OOOnOnOOOmmmININCNCO 


"lo 


00 roO O^'t iOrOO>M LOO O 10 to O O CN N CI O O COO 
rorOHQO ro 6i" O^ cooo <N O O "too ci 10 a w \0 O 1 coo On 


d co "3- tJ- 10 100 O N NOO 00OnOnOnOOOmmmoicni(N 


"lo 


O O "t On N m MOO «)C 00 OnOO O cO O O m O "t n co 
co ci 00 CI 00 PON MO O "3-00 01 O O r^N O "t N O "t N 


<N co "3" "3- "■) loo MO N noo ooooonOnOOOmmmcncncni 


lo 


10 m 1000 1000 Ncoc-O m m o* n ^f mO "3-O0 m -t n On 

CN CM O^ 1 ^ HO M O O !OC^ COO O "3-00 M LOOO M LOOO H ^~ 


N CO CO tj- 10 lOO O N N NOO OOO^O^OnOOOhi-hmcmcn 

MMMMMMMM 


** 


On ci ion ro 10 rOOO m co co cn O N -3- On "t 00 ci looO m co lo 
h moo -3-0 ioO -3- On co n m 1000 cn lo On ci On ci o* cn 


m co to -3- 10 100 O O N NOO oooooOO^OOOmmmcn 

M M M M M M M 


vd 

*■**- 


't 't <oO m moo cn 100 lo "t m n cooo ci O cn lo n c> O 
m O N CO O "too ")NH ioo> COO O CON ^t n coo O 


<N co co "t "3- ir> 100 O N N NOO ooOnOnOnOOOmmmcn 


%t- 


CO O i^3"NN coo 0000 n 10 m N ci NO "to O m ci "3- 10 

O OO <N N CN N M 10 C>CONH "3-00 M LOGO M "3" GO M "3" N 


cs cn co "3" "3" >o too O O n noo oOoQOnOnOnOOOmmm 


- 


m n "t cn "3-cjoO O m o 00 iomo m "3-00 O co loo noo O 

O 00 LO M O M lOO "3"O0 M Lo 0> <N O 0> CN O 0> CN IO00 m *t 


ci ci co "3" "3" io ioo O O N N noo 0000OnOnO-0 00>-iw 

M M M M M 


co 


»ooo "3"0 moo m cocom On 10 O logo NrfNaOHPinro 
On N -rt o lo On "3-O0 cio a co C" O co c- coo O coo 0* cn 


H <n co "3- "3- "3" lo too o O N noo 00000000000m 


"co 


0\0>tOc-C*NOO LOCI On ^" On COO O M CN "3" LO LOO o lo 

00 O cooo cooo o o O "3- N m rj-00 m "3-o0 m -3- N O coo On 


m <n co co "3- "3- lo ioo O O n N noo coco On On On O O O O 


CO 


<N O M "3-CSO0000O CNOO CON O C) LOO NOO s <^oo GO 00 

00O ci t^oo O "3-GO ci lo^cio C^c] loco m -^-r^O coO 


m ci cocO"3-"3->olo loo O O N t-» noo 0000 O0>00 O O 

M M M 


co 


loOOnmnom<~>Ocinm-^-ooOmcicncncimO<"> 
r^ioOO) O loocso O fON o coo O coo C\ ci looO m co 


m <n cocO"3--^-"3-lo ioo O O t- r-- r^oo oooooo OOOO O 


CM 


00 O r^O m co <n o O m logo O <n -<3-LoiOLOLO"3-"tcOM o 

O "3-(T>"3-0^cot^M -^-00 m "3-00 m -^-c^o coo oci logo m 


m o ci coco"3--3"Loio loo Mri i o r^ t>- tiod go od oo <> <r> o\ 6 


(N 


O <T>^-IM LOLOCOO iof>« LOO NOO GO GO oo t-^o LO CO o o 
O C100 CON H lOOCI LOO\<N LOGO M *^" f^ O COO O CJ LO00 


M CS CN CO CO «t 't 3" IO LO LOO O O t^ N f^00 00 O0 00 o a O 1 


N 


cioo 0000 r^"3-0 coo 00 O m m m m O Ooo n lo co m o> 
lo m N m io O COO O COO O COO Od UINO COO O* C4 "3- 
M CJ Oi cococOTh"3-LOLo LOO OOON-r^ N OO 00 OO M 0>0> 


O 


■tCiO O O 00 cot^O ci •*j--<t^t-"3--*J-coc! Oooo t)-ci <->r- 
"3"0 loO "3"t^M "3-00 m ^3-t-^O coo <T><n ion o coooo m 


M C) in cocorO'+"t-"J-LOLo LOO O O O r— r-~ t^-OO 00 00 OO On 


MN 


LO-^-M COM t^M "tO NOO CO NO LOCOM Q\N TO CI <T>0 CO 
CO O^ ^OO CI LO On C) LOGO M 3NO COO On m "3" N O CI LOOO 


M M CI o coroco3-3-3-ioio LOO O O O N N NOO 00 00 00 


•^ 


loOloiomoooOmmmOoonlooon loooOlocnOn 

CN 00 CI o O COO O COO On ci "3- N O COO 00 H Tj-O On CI "3- 


M M CI CI COCOCO'*"3-"3-"3-LOLO LOO O O O N N N NOO 00 


X 


"to 00 loOnci "t"t "t co« O 00 locoO r^"tO r^coOO ci 

MO O ""tNM "3-t^O COO On M Tt N O CI LOOO O COO 00 M 


M M CI CI CI COCOCO"3-"t"t T t l OlOLOOOOO NNNN00 


H 


co On "3"0 t^ r^o lo co m oo io ci OnO ci Onlom n co c»io 
O looO ci looO m "t N O co looO m coo Onm "t n a ci ^-t^ 


H M M CN CN C3 fOCOfO , t3'"t3*l01010 LOO O O O t^ f^ N 


X 


O cioo O O 0000 3- moo "tM nioOnioh nmoO -tON>o 

On COO O coo OO m "t n o> CI lONO CI 1O00 O CO LOOO O CO 


O m m ci ci CN d rororOco3 , "t"tlOiOlO IOO O O O r-^ t^ 




LO CI "t CO M OnO CO OnO m Nco ON3 O lomO CN r^CNOO CO 
N M 3-N O CN LOOO O COO 00 m COO On m -to On m "tO On 
O M M M CN CN CN CN COCOCOCO"t"t""t"tLOLOLO LOO O O O 


X 


O N"tM00 "tONLOOO MO M NCN NCNO0 <N00 <O00 COOO 
LOOO M "to Onm "tNONCN 3" N CMN "tNONCN ^-t^ONCl Tt 


O O M M M M CN CN CI IN cOcOCOCO"tt"t"tl01010 LOO O 


J3}9U. 


B >a 


H M M M CI CI CI CN COCOCOrO"t"t3 - 3 , l01010 LOO 



126 DRAWING DIES 

in which M = approximate mean height of drawn shell; // = 
height of drawn shell; t = thickness of shell; T = thickness of 
metal before drawing. After determining the mean height, the 
blank diameter for the required shell diameter is obtained from 
the table previously referred to, the mean height being used in- 
stead of the actual height. 

Example. — Suppose a shell 2 inches in diameter and 3! 
inches high is to be drawn, and that the original thickness of the 
stock is 0.050 inch, and thickness of drawn shell, 0.040 inch. 
To what diameter should the blank be cut? Using Formula (3) 
to obtain the mean height: 

,, /// 3.75 X 0.040 . , 

M = 77; = ° /J — 1 - = 3 inches. 
1 0.050 

According to the table, the blank diameter for a shell 2 inches 
in diameter and 3 inches high is 5.29 inches, the mean height 
being used when referring to the table, as previously mentioned. 
This formula is accurate enough for all practical purposes, un- 
less the reduction in the thickness of the metal is greater than 
about one-fifth the original thickness. When there is consider- 
able reduction, a blank calculated by this formula produces a 
shell that is too long. This, however, is an error in the right 
direction, as the edges of drawn shells are ordinarily trimmed. 
If the shell has a rounded corner, the radius of the corner should 
be deducted from the figures given in the table. For example, 
if the shell referred to in the foregoing example had a corner of 
j-inch radius, the blank diameter would equal 5.29 — 0.25 = 5.04 
inches. 

Another formula which is sometimes used for obtaining blank 
diameters for shells, when there is a reduction in the thickness 
of the stock, is as follows: 



D - 



y/<r + (a 2 -* 2 )^ ( 4 ) 



In this formula D = blank diameter; a = outside diameter; 
b = inside diameter; / = thickness of shell at bottom; // = 
depth of shell. This formula is based on the cubic contents of 



BLANK DIAMETERS 
Blank Diameter Formulas for Drawn Shells — i 



Shape of Body 



h k — *■ 



I 



< — — d, > 

k d-, H 



/i k d-, — 



Diameter of Blank /3 = 



Vrf 2 + 4 <f A 



Vd 1 « + 4 d 1 A + 2/(di+d 2 ) 



Vd 2 2 + 4 diA 



< — — dT >, 

$L J 

>,, < — d . — J 

_i J . 1 



k d 



feV — <** — nJ 



Vd 2 2 + 4 (dihi + difa) 



T 



*— i 

li 2 _K- % 







K d 



-ti *>, 





Vdo* + 4 (d^ + <2 2 A 2 ) + 2/(d s + dj 



Vd 3 2 + 4 (diAi + d 2 ho) 



V 2 d 2 = 1.414^ 




V^ 2 + d 2 2 



i^h^i'+Z^ + ^i) 



127 



128 DRAWING DIES 

Blank Diameter Formulas for Drawn Shells — 2 



Shape of Body 



Diameter of Blank D 




1. 414 Vd 2 + 2dh 




Vdi 2 + dr + Adih 




i. 41 4 vdi* + 2 dji + f fa + do) 



K- — <* — >• 



Vd- + 4 h- 




Vd,* + 4 h~ 




Vd l * + 4h* + 2f(d 1 + d 2 ) 



<- d >i 



ft, 




x ,/• ) .1 (//,- I <//;,) 



k d-„ 




y di* + 4 [hi 2 + dih, + { (<*, + d 2 )~\ 




W s ! + 4 (Ai 8 + <« 



BLANK DIAMETERS 
Blank Diameter Formulas for Drawn Shells— 3 



Shape of Body 



Diameter of Blank D 



I29 



j< dj- *\ 



'f 



Vd,2 + 2S (d!+ d 2 ) 



jf-di 



1 k — d 2 — >i ! 

u 



y/d{ + 2 s {d\ + di) + d 3 - d-:' 



— dr- 



-d, --»| 



V^ 2 4. 2 [ 5 (rf 1 + d 2 ) 4- 2 JaA] 



< d 1 



^ 



& t7 



Vdr' + e^rdi + Sr 2 ; or 



Vd 2 2 + 2.28 rd 2 — 0.56 r 2 



4? 



k d-5 — 



vr- 



l<- — d, 



Vd 1 2 + 6.28^ 1 + 8r 2 + 2/(^, + ^); or 



Vd 2 2 + 2.28 rd t + 2/ (dj 4- d») - 0.56 r 2 



k d- 2 H ! 

1 r 



V^ 2 4- 6.28 rdi + 8 r 2 + d 3 2 - d 2 2 ; or 



Vd 3 2 + 2.28 rd 2 - 0.56 r 2 




d~ 



W 



-— d T - 




VdS 4- 6.28 rdi + 8 r 2 4- 4 d s A + d 3 2 - d 2 2 ; or 



Vd-, 2 + 4 d 2 (0.57 r + h) — 0.56 r 2 



|<— d T - J 




v / d 1 2 + 6.28rdi4 r 8r 2 + 4^ + 2/(d 2 + d 3 ); or 
Y d 2 2 4- 4 d 2 f 0.57 r + h + A + 2 d 3 /- 0.56 r 2 



130 DRAWING DIES 

the drawn shell, K is assumed that the shells are cylindrical, 
and no allowance is made foi a rounded cornei al the bottom, 
in foi trimming the shell after drawing. To allow 1 < ► 1 trimming, 
add the required amount to depth h. When a shell is of irregu- 
lar cross- section, ii its weight is known, the blank diametei can 
be determined l>\ the following formula: 

"■■^ (5) 

in which D - blank diameter in inches; II' weight of shell; 
\c weighl oi metal pei cubi< inch; / thickness oi the shell. 

rhe tables "Blank Diametei Formulas for Drawn Shells," 
contain the formulas foi many common shapes. 

Phese formulas are based upon the long-established rule that 
the area of the blank equals approximately the area of the shell. 
It is also assumed thai the metal, which is comparatively thin, 
does not undergo any greal change of thickness while the flat 
blank is converted into a shell All corners at the bottom are 
shown sharp, which is a condition that is practically impossible 
to obtain in draw ing dies, as the metal will not stand the strain. 
The radius oi these corners should not be less than six to ten 
times the metal thickness for tin plate and lour to five times for 
eoppei plate, according to the quality. Otherwise, the table is 
sell explanator) and no furthei comment is necessar) 

Formation of Air Pockets in Dies. — When making drawing 
and forming dies, it is important to provide vent holes wherever 
the air would be compressed excessively in the operation of the 
die, it such vents do not exist Dies have often given trouble 
and even proved to be complete failures because oi the forma- 
tion of aii pockets Vent holes are needed, in some cases, to 
prevent the air from being entrapped between the work and the 
punch 01 die, and in other eases to facilitate removing or 
stripping a close-fitting cup 01 shell from a punch. For in- 
stance, it an ail pocket is formed hetween the end oi the cup 
and a forming punch, the air compression may be high enough 
to burst the end of the cup. The remedy is to drill a vent hole 
into the aii pocket so that the aii can escape Drawing punches 



i.iiiii-n \] n\ i «»r mw u [NCJ i ', i 

:m nihil prOVidfid Willi in;ill v<nl holes wln< li i.hii'l liom 

the end oi the puni h to somi poinl bi , < > 1 1 < I iii< top oJ thi <Ii:iwm 

:.Im II Mii. v<iil .illnw', lli< .111 l'i i nli i till RpHCI l>< I v/<< n till 

• mi oJ tin punch and the bottom oi the shell when thi lattei 
li being stripped) thus pi i v< n i mi' iii« formation ni .1 |.,uii,ii 
vacuum which would Interfere wiih the removal oi thi worl 
The pressun | ..i< i ., ..I blank holders, on dies ol the combination 
i,i- .'.i.m inn. , ..in., trouble i>y compressing thi ah as they 
descend during thi drawing operation This compression Is, ol 
course, more pronounced when the supporting pins which con 
ii< ' i wiih iIm rubbei pressure attachmeni are closely fitted to 
iii< holes hi i in base ol the die An vents tire sometimes formed 
i<<i Mm space beneath the pressure pad, by simply cutting small 
slots <»i grooves along the supporting pins, thus providing oul 
lets i "i the •hi as thi pressure pad descends during I hi drawing 
operation Much depends upon thi location oJ the venl holes 
I'm instance, sometimes when q v<ni is reciuired til thi end (, i 
lie forming punch, ii ii«>ui«i i>< placed til one side rathei than 
in id. centei ol the punch, because the aii Is entrapped ai the 
"ni. i cornei ol the cup as the lattei Is pressed to Its final shape 
IJefore drilling venl holes, the action «»i the die should b< can 
fully studied The effeel which s venl holi mlghl have upon 
i ii« strength oi ti i >• i r i < li <n die should tilso be considered When 
iin parts ol the die have no! been closely fitted togethei 'i«i 
haps because accuracy was unnecessary) venl holes may nol be 
in < «i( <i 

l.ulii i< mil. fin I >i .i 7/iiij- .iikI I 1 oi iniiip. I 1 mi . 1 1 .!,', in;' I <( I the 

lollowni)/ mixture is recommended as ;| lubricant ", i>«i cenl 
fluked graphitej ", pel cenl beel i;ill<»w, nod <\a p<*i mil i.-ml 
ml 'iin. mixture should be heated and the worli dipped into 
ii Oildag nil-... i wiih heavy grease i'. also used foi steel, and q 
ilnn mixture oi grease (preferably tallow) and white lead has 
proved satisfactory The following compound is also used foi 
drawing nheel steel ol ti miM grade Mr-, one pound ol whiti 
lead, one quart ol fish oil, three ounces ol u.ni. lead, and oni 
jiini oi watei These ingredients should be boiled mod thoi 
oughly mixed A mixture oi white lead and kerosem i tilso 



132 



DRAWING DIES 




i I 



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Machinery 



Fig. 3. Drawing Dies for the Successive Operations Illustrated in Fig. 4 

recommended for steel, especially for heavy drawing operations. 
For working brass or copper, a solution composed of 15 pounds 
of Fuller's soap to a barrel of hot water (used hot), or any soap 
strong in rosin or potash, is cheaper and cleaner than oil. The 
stock should pass through a tank filled with this solution before 
entering the dies. For drawing aluminum, vaseline of a cheap 
grade is sometimes used. Lard oil is also applied to aluminum 



ANNEALING DRAWN SHELLS 



133 



when drawing deep shells. Kerosene is used for drawing alumi- 
num and is said to prevent the dies from becoming "loaded" 
as the result of the abrasive action of the metal. For com- 
paratively deep drawing, a lubricant having more "body" 
should be used. Incidentally, kerosene is also used when cut- 
ting aluminum in blanking dies. Aluminum should never be 
worked without a lubricant. Zinc may be lubricated with 
kerosene, and it is sometimes warmed as well as lubricated, to 
facilitate drawing. For many classes of die work, no lubricant 



-M 



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Machinery 



Fig. 4. The Blank and Successive Drawing Operations for Producing 
Steel Shell E 

is required, especially when the metal is of a "greasy" nature, 
like tin plate, for instance. 

Annealing Drawn Shells. — When drawing steel, iron, brass, 
or copper, annealing is necessary after two or three draws have 
been made, as the metal is hardened by the drawing process. 
For steel and brass, anneal between every other reduction, at 
least. Tin plate or stock that cannot be annealed without 
spoiling the finish must ordinarily be drawn to size in one or 
two operations. Aluminum can be drawn deeper and with less 



134 DRAWING DIES 

annealing than the other commercial metals, provided the 
proper grade is used. In case it is necessary to anneal aluminum, 
this can be done by heating it in a muffle furnace, care being 
taken to see that the temperature does not exceed 700 degrees F. 

Dies for Drawing a Cylindrical Shell. — A set of drawing dies 
for producing a cylindrical steel shell, 4 inches in diameter and 
8f inches long, is shown in Fig. 3. The successive operations 
are illustrated in Fig. 4. The flat circular blank from which the 
shell is drawn is made of sheet steel, j$ inch thick and i2§ 
inches in diameter. This flat blank is first drawn into the form 
of a shallow cup B which is reduced in diameter and lengthened 
to the required size by operations C, D, and E, as Fig. 4 indi- 
cates. The first drawing or cupping die is illustrated at A, 
Fig. 3. The die-bed a is made of cast iron and the drawing die 
b, of machine steel, pack-hardened. The punch c is also made 
of machine steel and pack-hardened, whereas the blank-holder d 
is of cast iron faced with a hardened machine steel ring e. The 
cup is stripped from the punch by means of a finger / which is 
backed by a spiral spring and engages the top of the drawn 
part when the punch ascends, thus stripping it off. Many dies 
do not have these stripping fingers, the work being removed 
from the punch, when the latter ascends, by contact with the 
lower edge of the die. The use of stripping fingers, however, 
gives a more positive action and they are particularly desirable 
for deep drawing operations. 

The construction of the die for the second operation (see view 
B, Fig. 3) is practically the same as the one just, referred to, ex- 
cept that it is provided with a gage plate g for centering the cup 
with the die. An inside blank-holder n is also used for steady- 
ing the cup while it is being redrawn. The size of the shell 
produced in this die is indicated at C, Fig. 4. After these two 
drawing operations the shell is annealed and is then put through 
die C. As will be seen, this die is also equipped with an inside 
blank-holder and a gage plate for centering the shell to be re- 
drawn. The cup, D, Fig. 4, after the third drawing operation, 
was too long to be inserted in the press available for the fourth 
drawing operation, and had to be trimmed to a length of 7! 



DRAWING SPHERICAL COVERS 



*3S 



inches. It was then redrawn in die D. The shell is kept in an 
upright position in the die by guide h, which fits in the top of 
the shell and holds it while the punch descends. The distance 
between the bed and ram of the press was not sufficient to allow 
the use of this guide without trimming the shell; this operation, 
however, could have been dispensed with if a suitable press had 
been available. Prior to the final drawing operation, the shell 
was annealed and after being drawn was trimmed to the re- 
quired length. This last drawing die is provided with a knock- 
out k, which is necessary because it is impossible to force the 




Machinery 



Fig. 5- Triple-action Die for Drawing Spherical-shaped Covers 

shell through the die in this operation on account of "a small 
15-degree flange which had to be formed around the top edge, 
as indicated in Fig. 4. All of the drawing punches are provided 
with air passages to facilitate stripping the work. 

Drawing Spherical Covers. — A punch and die for drawing 
spherical covers to the full depth in one operation without leav- 
ing a wrinkle, and finishing four at a time, are shown in Figs. 5, 
6, and 7. The shape of the drawn part is indicated by the heavy 
line in Fig. 7. As is well known, it is difficult to draw a shell to 
this shape in one operation by the use of a standard double- 



136 



DRAWING DIES 




Machinery 



Fig. 6. View Showing First Stage of Spherical Cover Drawing Operation 




Machinery 



Fig. 7. 



Relative Positions of Punch, Die and Pressure Ring when 
Spherical Covers are Drawn 



action die, because the stock tends to wrinkle and tear, making 
it necessary to remove the wrinkles by another operation. To 
enable this work to be done in one operation a triple-acting die 
for use in a double-acting press was designed. Fig. 5 shows the 
relative positions of the punch, pressure ring, and blank-holder, 
just before the drawing operation begins. The action is as fol- 
lows: After the four blanks have been placed in position on the 
top face of die A, blank-holder B descends until it holds the 



DRAWING SPHERICAL COVERS 



137 



blanks firmly against the die face. The pressure ring D (which 
is backed up by heavy springs that are strong enough to form 
the first drawing operation) then descends to the position in- 
dicated in Fig. 6. This pressure ring then acts as an inner 
blank-holder while the punch descends to the bottom of the die, 
thus forming the central part of the blank, as indicated in Fig. 
7. The action of this die was perfect and no defective shells 
were produced, the drawing being easy and uniform. 

The die is made of cast iron and provided with a vent hole, 





Machinery 



Fig. 8. 



First-operation Die for 
Can Nozzles 



Fig. 9- 



Redrawing Die for 
Can Nozzles 



as shown, through which the ejector operates. The drawing 
faces of both the die and blank-holder conform to the size of 
the blank. The blank-holder is of the regulation double-action 
type and is made of cast iron. Both the die and blank-holder 
are secured to the press by means of a clamping flange. The 
pressure ring is held in position by several screws E between 
which are the pockets which contain the heavy spiral springs. 
These covers are of a large size, ranging from 15 to 22 inches in 
diameter. 

Drawing Dies for Making Tin Nozzles. — Dies for the pro- 
duction of nozzles for tin cans of large sizes are illustrated in 



138 



DRAWING DIES 



Figs. 8 to ii inclusive. These dies, with the exception of the 
one for the finishing operation, are of the combination type and, 
therefore, used in single-action presses. The die for the first 
operation is shown in Fig. 8 and is composed of the following 
principal parts : A bolster plate A ; a blanking die B ; a draw- 
ing punch C; and a pressure ring or blank-holder D, which rests 
upon three pins connecting with the rubber pressure attach- 








Machincry 



Fig. io. 



Die for Third Operation on 
Can Nozzles 



Fig. ii. 



Die for Finishing 
Can Nozzles 



ment P for regulating the pressure while drawing the shell. 
The combined blanking punch and drawing die G is fitted on 
the outside to blanking die B, whereas, the inside diameter 
equals the diameter of the drawing punch C plus twice the 
thickness of the stock. The forming pad // within the punch is 
made to fit the top of the drawing punch for forming the top of 
the shell at the end of the stroke. As will be seen, this part also 
serves as a knockout for the drawn shells. This die is oper- 
ated by a press of the inclinable type. The punch, as it comes 
into contact with the blanking die B, cuts the blank which is 
then held by pressure ring D against the end of punch G; as 
the punch descends, the blank is drawn over the drawing punch 



DIES FOR NOZZLES 139 

C and when it moves upward the stem of the knockout comes 
into contact with a bar in the press, thus pushing the pad H 
down and forcing the shell out. The form produced in this die 
is illustrated at A, in Fig. 12. 

The die for the second operation is shown in Fig. 9. The 
center block or drawing punch C of this die is tapered, and the 
punch F is also bored out to a corresponding taper. The pad 
G in the punch is of a peculiar shape, as will be noticed; the 
reason for this shape will be explained later. The shell is placed 
on the drawing ring B and the punch, as it descends, draws it 
down and compresses it to the shape of the punch C. The shell, 
which now resembles the form shown at B, Fig. 12, is knocked 
out on the up-stroke by the engagement of stem H with the 
knockout bar, the same as in the first operation. 




uncsi 



r- x 16 

1ST OPERATION 2ND OPERATION 3RD OPERATION 4TH OPERATION 

Machinery 



Fig. 12. Successive Operations Performed in Dies Illustrated in Figs. 8 
to 11 Inclusive 

The die for the third operation, which really consists of three 
operations, is illustrated in Fig. 10. The principal parts are the 
trimming die B; the center block C; the drawing ring D; the 
lower die E; and the tube G, through which the bottom of 
the nozzle passes after being punched out. Incidentally, these 
bottoms are used for roofing shells for fastening tar paper in 
place on roofs, etc., so that two articles are made at once. In- 
asmuch as these blanked out ends are to be utilized in this way, 
they are formed by pad G (Fig. 9) in the second operation. 
The die for the third operation is also used in an inclined press. 
As the punch M descends, it cuts out the bottom and at the 
same time punch H trims the flange. As the downward move- 
ment continues, the shell is pressed over the edge of center 
block C. When the punch moves upward the knockout bar 
comes in contact with stem N, thus forcing the cross-pin K and 



140 DRAWING DIES 

stripper / down and ejecting the nozzle, which is now shaped 
as illustrated at C, Fig. 12. 

The die for the fourth and finishing operation is illustrated 
in Fig. n. This is of simple form and yet much depends upon 
it, because the nozzles all have to be of uniform size on the 
finished edge in order to receive a sealing cap, which, when 
closed, must be water-tight. The die has a bolster plate A ; a 
die-block B of tool steel, hardened and tempered; and a punch 
P which is also hardened and tempered and ground out to fit 
a gage. In the operation of the die, the nozzle is slipped over 
the die-block B ; as the punch descends, the recess at F engages 
the edge which was partially curled over in the preceding die, 
thus completing the curling operation and pressing it to the 
shape illustrated at D, Fig. 12. As the punch rises, the shell 
is ejected by an automatic knockout which is of the usual form. 

Drawing a Flanged and Tapered Shell. — When drawing 
tapered shells with flanges, the requirements for the construction 
of the dies and the method of forming the shells are different 
than when drawing cylindrical shells, especially if the taper of 
the finished shell is large in comparison with the height and 
diameter. The blank should first be drawn into a cylindrical 
shape or one having a slight taper, the area being equal to that 
of the metal required in the finished shell. When trouble is ex- 
perienced in drawing tapered shells, it is almost invariably 
caused by an attempt on the part of the diemaker to produce 
a "steep" taper in the first operation, or to draw a tapered shell 
directly from the flat blank. If this practice is followed, the 
shell may either split at the bottom or waves and wrinkles are 
formed which cannot be removed. Another frequent cause of 
trouble is due to a surplus of metal in the shell with the result 
that it cannot be distributed in the finishing operation or be re- 
turned to the flange from which it was drawn. 

The successive operations in producing a flanged, tapered shell 
having diameters of if inch and 1 inch at the large and small 
ends, respectively, and a depth of i/g inch with a flange 2§ 
inches in diameter, are shown by the diagrams A, B, C, D, and 
E, in Fig. 13, together with the drawing dies. The flat blank 



DRAWING A TAPERED SHELL 



141 



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142 DRAWING DIES 

A is, in three operations, drawn to shape D, which is slightly 
tapering, as the diagram shows. When the proper amount of 
metal is contained in the shell illustrated at D, a succeeding 
operation of re-forming — not drawing or reducing through 
friction — will shape the cylindrical shell to the desired taper, 
as indicated at E. The reason for this practice of keeping the 
shell cylindrical (or nearly so) until the last operation, is that in 
drawing a cylindrical shell or one that is slightly tapering, the 
metal is confined at all times during the process of drawing, be- 
tween the die and punch surfaces, making the formation of 
wrinkles impossible and the flow of metal equal and constant 
during the entire operation. When the depth to be drawn is 
quite shallow, as compared with the depth of the shell diameter, 
even steep tapers can sometimes be drawn in one operation. In 
general, however, taper parts having a diameter at the bottom 
which is small in proportion to the extreme diameter of the 
flange, are difficult to draw, because of the formation of wrinkles 
and also because of the small area at the end of the drawing 
punch (in comparison with the large surface around the flange) 
and, consequently, the weakness of the metal at this point. 

The blank A for producing the shape shown at E is 3 inches 
in diameter and 0.032 inch thick — No. 20 Brown & Sharpe 
gage. The blank was cut in a plain blanking die. The second 
operation B was done in the die shown at F and also the re- 
drawing operation C, the die remaining unchanged except that 
a thinner locating pad and blank-holder was substituted for the 
one shown at h. Referring to the sectional view F, the drawing 
die is at/; the shell knockout or ejector at g; the blank-holder 
and locater at h; the drawing punch at i; two of the five rub- 
ber pressure attachment pins at 7; the die bolster at k; the top 
rubber pressure attachment washer at I; and the rubber "spring 
barrel" or pressure attachment at n. The die for producing the 
shape shown at D is illustrated at G. The cup C is located on 
the punch and the die p descends and draws the cup to shape 
D. This die is also equipped with a rubber pressure attach- 
ment. In the finishing punch and die, illustrated at H, no 
drawing of the metal takes place, the wall of the shell being re- 



DRAWING A TAPERED SHELL 1 43 

shaped or formed in order to produce straight tapering sides. 
In the operation of this die, the shell D is located in a seat in 
the holder q and the die r descends, holding the flange of the shell 
tightly between the faces of q and r while the punch s forms the 
shell into the tapered shape. At the bottom of the stroke, 
pressure occurs on all the surfaces of the shell, thus producing a 
smooth tapered form. 

Referring to the diagrams showing the evolution of the shell 
from the flat blank, it will be noted that at C an increase of \ 
inch in height and y 1 ^ inch in top diameter is obtained. At D 
the height is increased to i-jg inch (a gain of f inch), whereas at 
F the shell is completed to a height of iy 7 g inch, the smallest 
diameter being 1 inch and the largest if inch, as previously 
mentioned. The dotted line on the blank at A shows the 
amount of metal drawn from the blank in forming the cone of 
the shell at E. In producing this shell, the following changes 
take place in the thickness of the wall and flange. Referring to 
sketch E, the metal is reduced to 0.030 inch at c, to 0.022 inch 
at d, to 0.018 inch at e, and to 0.021 inch on the end or bottom 
of the shell. 

It was necessary to anneal the shell after the first and third 
operations. To secure satisfactory results, annealing has to be 
done without producing a surface scale because the scale would 
impair the smoothness and accuracy of the finished product. 
Thin lard oil was used as a lubricant during the first two oper- 
ations and then the shells were run dry and clean during the 
last two operations. None of the shells were fractured, and the 
tools shown in the illustration produced a large quantity. The 
drawing pads, punches, and rubber buffer pins used in the dies 
F and G were made of steel and the other parts of cast iron. 
For the finishing die H, steel was used throughout for the work- 
ing parts and the pad and die surfaces were hardened and 
lapped. When drawing taper shells of the type referred to, in 
which a uniform thickness of metal throughout the wall of the 
shell is not necessary, a slight lack of metal in the cup next to 
the last operation is preferable, because the finishing tool can 
then stretch the metal so as to produce a smooth, true surface. 



144 



DRAWING DIES 



Die for Drawing in a Single-acting Press. — A die for draw- 
ing steel cups, such as would usually be made in a double-acting 
press, is shown in Fig. 14. No double-acting press was avail- 
able, but only a long-stroke single-acting press of sufficient 
capacity to do the job. The die was made as follows: On the 
die B were bolted some U-shaped pieces E which carried the 
holding hooks D. These hooks D could be adjusted to any de- 
sired degree of tightness by setting down the pieces E with the 
set-screws provided and then clamping them securely in place. 



RAM OF PRESS 




Machinery 



Fig. 14. Die for Drawing Cups in a Long-stroke Single-action Press 

The blank-holder C was suspended on four bolts G, and these 
bolts were adjusted to the proper length so that the blank- 
holder C was laid on the blank early in the stroke; then closing 
lugs F engage the holding hooks D and force them in on the 
beveled ledge of the blank-holder. The lugs F then slide along 
the back of hooks D during the remainder of the stroke. 

On the up-stroke the closing lugs leave the hooks D which are 
immediately thrown open by springs provided for this purpose, 
and then the blank-holder C is lifted up by the suspension bolts 
G. The formed piece is loosened in the die by the rubber block, 



DRAWING, FORMING, AND BLANKING DIE 



145 



or, if necessary, a positive stripper can be provided. At first 
the closing lugs F were made solid with the punch-holder, but 
after several were broken by dirt or other foreign substances 
getting under the blank, a new holder was made with the lugs 
bolted on, so that the bolts would allow the lugs to give enough 
to prevent breakage. This die is more expensive than would 



T7" 




A— Id 




FINISHED PIECE 



i ! i 



M n 11 
1 1 1 11 

J L _U_J LILJ 



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PLAN OF DIE AND STRIPPER 




CUTS OUT WEB BETWEEN 
BLANKS AND ALLOWS 
STRIP TO SLIDE ALONG 



Machinery 



Fig. 15. Punch and Die for Performing Five Separate Operations 

be required for a double-acting press, but makes it possible to 
do the work with the equipment at hand. 

Drawing, Forming, and Blanking Die. — The die shown in 
Fig. 15 performs five distinct operations before the piece shown 
in the upper right-hand corner of the illustration is dropped 
completed from the press. In constructing this die it was not 
deemed practicable to make it of one solid piece, since one small 
flaw would, in this case, spoil the entire die. A die-block of 
machine steel was, therefore, used, having recesses counter- 



146 



DRAWING DIES 



bored for the insertion of tool steel bushings. In using a die 
containing two or more punches, considerable trouble is some- 
times experienced on account of the variation in width of the 
stock to be punched. Should the stripper be planed to fit one 
of the strips of stock very nicely, the chances are that the next 
strip would not enter the stripper at all. The part N, shown in 
the plan of the die, enables this trouble to be overcome in a novel 
and practical way. The stripper is planed out fa inch wider 
than the stock and recessed to allow the spring guide TV to slide 
freely when the stripper is in position in the die. By glancing 
at the sketch the reader can readily see how the springs keep 




Fig. 16. 



Aluminum Shell Produced in Dies Illustrated in Figs. 17 
to 19 Inclusive 



the stock pressing against the gage side of the stripper. The 
punch A does not perform any work pertaining to the finished 
blank, but is used for cutting out the web in the stock in order 
to allow the strip to move along until the next web touches the 
stop-pin. As the stop-pin P does not come out of the stock it 
is therefore impossible to "jump" the stock and make a miscut, 
which would mean disaster to the drawing and forming punches. 
After setting up the die in the press, the punches of course 
descend five times before a single finished piece appears, but 
thereafter a finished piece drops at each stroke of the press. 
The first punch, beginning at the left, indents the stock, and the 
punch is so adjusted that the face of the punch levels the stock. 
The second punch pierces the bottom of the indentation. The 



BLANKING, DRAWING, AND EMBOSSING DIE 



147 



next punch draws the stock, and at the same time forms a small 
feather along the hole in the finished piece. The fourth punch 
is the forming punch, and the last punch does the blanking. 

Blanking, Drawing, and Embossing Die. — The spoked alumi- 
num shell shown in Fig. 16 is about four inches in diameter and 
one inch deep. It has four spokes, or arms, radiating from a 
hub in which a shaft hole and four rivet holes are punched. 
These holes are used for attaching the aluminum shell to the 
bearings of the hub on which it is used. Stiffening "lips" are 
formed around the openings and spokes, and the ribs or spokes 







R. 








*** 


1 




1 




HHk 








A-m JLfl 




/ k 


/ 












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Machinery, N. Y- 



Fig. 17. 



Combination Blanking, Drawing and Embossing Die for 
Aluminum Shell 



themselves are embossed to add to the strength of the shell. 
Four rivet holes punched through the rim of the shell serve to 
attach it to an exterior band. 

This shell was made in the following manner and with ex- 
cellent results: The blanking, drawing, and embossing is done in 
one operation in a double-action press, using the die shown in 
Fig. 17. The blank-holder A is made of cast iron, and a hard- 
ened tool-steel blanking die D is fastened to it, which not only 
acts as a die, but also serves to hold the blank in position while 
the drawing operation is taking place. B is the cast-iron draw- 
ing punch, to which is attached a hardened steel face K. This 
face K contains the embossing recess for the spokes, into which 
the metal is forced by the embossing punch H held to the lower 



148 



DRAWING DIES 



member. The punch H also acts as an ejector after the draw- 
ing and embossing operations have been completed, and is 
actuated by the stem / and the press knockout mechanism. 

The die-shoe C is made of cast iron and is bored out to re- 
ceive the blanking punch G, over the inner edge of which the 
shell is drawn after blanking. The stripper ring E, which is 
made of soft steel and passes around the periphery of the die G, 
is limited in its travel by the shouldered screws F, and is acted 
upon bv six helical springs. There are several vent holes in the 




Machinery. y. 7. 



Fig. 18. Combination Piercing and Ribbing Dies 

drawing punch and through the plate H and the base of the 
die-shoe, the purpose of which is to allow the air to escape while 
drawing, and enter while stripping and ejecting the shell. The 
shell is drawn entirely into the ring G and, of course, must be 
trimmed afterward. This is performed in a trimming lathe, al- 
though similar shells are sometimes drawn to the depth required, 
and a flange left on them, so that they may be trimmed off by 
a simple blanking die. However, the method of handling this 
operation lies entirely with the designer, although it should be 
governed to some extent by the requirements of the shell. 

After the shell is drawn into cup form, the next operation is 
to blank the openings to form the spokes and turn up the "lips" 
around these openings. Both these operations are performed 



BLANKING, DRAWING, AND EMBOSSING DIE 



149 



in the die shown in Fig. 18, which is used in a single-action press. 
The die-shoe A and the punch-holder B, respectively, are made 
of cast iron, the die-shoe being bored out to receive the soft- 
steel die carrier G and the ejector plate F, which is also made of 
soft steel and is actuated by four studs / resting on a cast-iron 
plate L. This cast-iron plate L is pressed upward by a rubber 
pad M which slides on stud K. The die-bushings E are flanged 
on the bottom, as shown, and are held in the carrier plate in 
the usual manner. They serve not only as dies for piercing, 
but also as drawing punches to draw the stiffening "lips" on 
the shell. The drawing die C is held on the punch-holder B 




Machinery, N. Y. 



Fig. 19. Die for Piercing Holes in Sides and Bottom of Aluminum 
Shell Illustrated in Fig. 16 

and carries the piercing punches D, which are set ahead of the 
drawing die so that they will pierce the stock before the die be- 
gins to draw the "lips." A stripper ring H, actuated by coil 
springs as shown, is limited in its travel by the drawing die C 
upon which it comes to rest on the up-stroke of the ram. All 
the screws and dowel-pins used for holding the various members 
in their respective holders are omitted for the sake of clearness. 
The shell is now ready to have the holes around the rim and 
the small holes in the bottom pierced. These operations are 
done in the die shown in Fig. 19 which is used in a single-action 
press. A circular disk B of cast iron serves as a base for the 
die, and to it is attached the die-anvil K, of soft machine steel. 
Die-bushings L and M are driven into the anvil K for piercing 



150 DRAWING DIES 

the holes in the rim and in the bottom of the shell. Recesses 
are cut in the block A' to receive the "lips" around the spoke 
openings. The cast-iron punch-holder carries two flat springs 
/, which serve to hold the shell on the anvil when the holes are 
being pierced. The punch-holder also carries four studs F 
(only two of which are shown) that operate the piercing punches 
G. These piercing punches G lit in blocks H held to the die- 
bolster, and are retained in the blocks H by the small studs N 
working in elongated holes in the block. These small studs or 
pins N also serve to prevent the punches G from turning around, 
so that their beveled ends are always presented properly to the 
studs F. The punches G are withdrawn by coil springs, as 
shown, when the ram of the press ascends. The punches O and 
P, for piercing the holes in the bottom of the shell, are held in 
a machine-steel block C, which is backed up with a hardened 
tool-steel block D inserted in the punch-holder. The blocks C 
and D are doweled together and held to the punch-holder. 

Making this aluminum shell in the manner described gives a 
uniform product, and the tools are of such a character that they 
are not very costly and are easily repaired. While these tools 
are of a special character, a number of the features incorporated 
in them could be used for a variety of purposes. 

Drawing Cartridge Cases. — The drawing of cartridge cases 
from sheet brass requires some interesting tools and methods. 
The practice referred to in the following is that of the Frankford 
Arsenal, and covers more particularly the drawing of cases for 
0.30 caliber cartridges. The first operation in the making of a 
cartridge case is to produce a cup, then by successive redrawing 
operations this cup is reduced in diameter and extended to the 
required length. Fig. 20 shows the various steps in the sequence 
of redrawing operations following that of making the cup. 
From this illustration it can be seen that five operations are 
necessary to bring the case to the required length. These are 
called redrawing operations because the work accomplished con- 
sists in reducing and redrawing a piece that has already been 
drawn to cup form. The press used for making the cups from 
which cartridge cases are made is of the double-action type, and 



DRAWING CARTRIDGE CASES 



151 




152 



DRAWING DIES 



carries four punches and dies, thus making four cups at each 
stroke. This punch press operates at ioo revolutions per 
minute, producing 400 cups a minute, or 24,000 cups per hour. 
The type of blanking and cupping die used in this machine is 
shown diagrammatically in Fig. 21. At A the blanking punch 
is shown in contact with the top face of the brass sheet; at B 
the blanking punch has cut out a disk of the required size and 
carried it down to the first shoulder in the combination blank- 
ing, cupping, and drawing die; at C the drawing punch has 
come into operation and has started to form the blank to cup 




Fig. 21. Action of Blanking and Drawing Punch in Producing Cup from 
which Cartridge Case is Drawn 

shape; and at D the blank has been forced completely through 
the die and has been given the first drawing operation. 

The sheet stock is held on a roll located to the right of the 
machine and is drawn into the press under the blanking and 
drawing punches by means of feed rolls. After the stock passes 
through the rolls, it is oiled by means of a cloth saturated with 
lard oil. 

Redrawing Operations on Cartridge Cases. — After the cups 
are made it is the general practice to anneal, wash, and dry 
them. Then they are ready for the first redrawing, or second 
drawing operation. The temperature to which the cup is 
heated for annealing varies from 1200 to 1220 degrees F. The 
manner of handling the cups after they have been annealed, 



DRAWING CARTRIDGE CASES 1 53 

washed, and dried, is to carry them in trucks, which are lifted 
from the floor of the annealing room to a track located above 
the drawing presses. These trucks are provided with false 
bottoms and are run along the track until they are directly 
over the hopper which feeds the cups to the punch press. The 
false bottom is then removed, allowing the cups to drop from 




Fig. 22. Drawing Press Equipped with Four Dies and Operating 
on 24,000 Cartridge Cases Per Hour 

the chute into the hopper A of the drawing press, Fig. 22, from 
which they are removed by a feeding device consisting of a 
wheel in which pins B are set at an angle of about 45 degrees 
with its horizontal axis. These pins are pointed, enabling the 
shell to be located on them mouth first. The pins are rotated 



i54 



DRAWING DIES 



inside the hopper so that they catch the cups and deposit them 
in close-wound spring tubes C. These tubes pass from the hopper 
down to the feeding slides of the drawing press and as the shells 
drop out of the tubes they are caught by fingers held on the 
slides and carried over into line with the dies and punches. 




Fig. 23. 



Duplex Drawing Press for the Fourth Redrawing Operation 
— Capacity 10,800 Cups Per Hour 



When the slides have advanced to their extreme forward po- 
sitions, the punches descend and force the cups through the 
drawing dies, depositing them in a box located under the press. 
The slides are operated from the crankshaft through bevel gears 
and a connecting-rod that transmits power down to a horizontal 



DRAWING CARTRIDGE CASES 155 

shaft carrying a series of four cams. These cams contact with 
rollers held in the feeding slides and thus transmit the desired 
movement to them. The rolls are held in contact with the cams 
by coil springs. The machine shown in Fig. 22 operates at 100 
revolutions per minute, and as four cups are drawn per stroke, 
it is evident that this machine has a productive capacity of 
24,000 cups per hour. The drawing press shown in this illustra- 
tion is used for the second and third redrawing operations, 
shown with the die and punch used at B and C in Fig. 20. 

The first, fourth, and fifth redrawing operations are handled 
in machines of a type similar to that shown in Fig. 23, which 
are provided with only two punches and dies instead of four, 
as was the case with the machine shown in Fig. 22. The feed- 
ing of the shells to the slide that carries them to the dies is 
practically identical with that shown in Fig. 22, but the slide is 
operated in a different manner. In this particular machine the 
slides A , which serve as a means for carrying the cups from the 
feeding tubes B over into line with the drawing dies, are actuated 
by means of a bellcrank lever receiving power from a cam held 
on the crankshaft C of the press. 

While the shells are fed to the punch with the mouth up, it 
sometimes happens that one will pass down the feeding tubes to 
the slide the wrong way, that is, with the bottom up. Now 
should such a shell be allowed to pass over into line with the 
die, it would mean that the punch would be broken and the die 
either broken or damaged to such an extent that it would be 
unfitted for use. It is not uncommon also to have shells pass 
down to the slide, that are dented or otherwise defective thus 
preventing them from feeding into the die properly. Should 
such a shell pass down the feeding tubes and stick in one of the 
slides, it would mean that the punch would come down on the 
slide and break. In order to provide against such accidents, 
an ingenious tripping device has been applied to this machine 
and works very satisfactorily. This device, while compara- 
tively simple in construction, is positive in its action, and has 
been the means of saving a lot of money in the cost of dies and 
tools. It also enables one operator to run four instead of two 



156 



DRAWING DIES 



machines. Essentially, this device consists of a projecting stud 
which is held in the crankshaft of the press, and, when the feeding 
slide is operating normally, passes through a slot cut in a lever 
that is connected with the bellcrank lever operating the slide. 
Now, if for any reason the slide should be prevented from making 
a complete forward or backward stroke, this- projecting pin 
would not pass through the slot in the lever mentioned, but 
would force the lever out, knocking out the lever Z), which 
transmits a movement through the links E and F and bell- 
crank G down to the tripping lever H. This knocks the clutch 
operating lever I off the catch — throwing out the clutch and 




Fig. 24. Automatic Trimming Machine for Cartridge Cases 

stopping the press. It can therefore be seen that this tripping 
device is of simple construction, but is effective, owing to the 
fact that when the slide does not complete its movement the 
clutch is thrown out before the ram of the press reaches the top 
of the stroke, so that the machine is stopped before it has a 
chance to complete another stroke. 

Final Redrawing Operation. — The fifth redrawing operation 
is accomplished in a press equipped similarly to that shown in 
Fig. 23. These presses operate at 100 revolutions per minute 
and turn out 12,000 cups per hour. Several annealing oper- 
ations take place between the time when the cup leaves the first 
redrawing operation and the time when it is ready for trimming. 



DRAWING CARTRIDGE CASES 157 

Before the fourth redrawing operation is done, the shells are 
taken to a heading machine of the horizontal type where they 
are "bumped," in order that in the successive redrawing oper- 
ations the head of the shell will not be reduced too much in 
thickness. The 0.30 caliber cartridge case has what is known as 
a solid head; that is, the top portion of the shell that contains 
the primer is not indented to form a pocket for the primer, the 
pocket itself being simply a hole forced into the head. This 
type of cartridge has been found necessary for use with smoke- 
less powders. The former method used in making 0.30 caliber 
cartridge cases was to form the pocket by forcing in the head, 
which was very little thicker than the sides of the shell near the 
head. This construction, however, was found to be too weak 
for smokeless powders, as the head would blow off. The 
"bumping" is a very simple operation and is somewhat similar 
to heading except that the punch is perfectly flat and simply 
gives the shell a blow, upsetting it slightly and flattening it so 
that in the two final redrawing operations — fourth and fifth — 
the metal at the head is not stretched to any appreciable extent. 
Trimming a Cartridge Case to Length. — It is practically im- 
possible to draw a shell that does not have an irregular top edge 
and also one that is not distorted or cracked to some extent. 
This makes it necessary to draw the case much longer than 
actually required and to trim off the surplus material. The re- 
moval of this excess amount of stock is done in machines that 
are operated automatically. These trimming machines are 
arranged in such a manner that the various hoppers can be 
filled from -an overhead conveying system. This arrangement 
consists of a track similar to that used in the drawing press de- 
partment previously referred to, and enables one man to attend 
to an entire line of presses. The track accommodates a truck 
in which the shells are carted along the line and from which 
they are ejected through a false bottom, dropping into the 
hoppers located over the machines. The feeding of the shells 
down to the trimmer is effected by the same type of hopper as 
previously described, but the subsequent handling is somewhat 
different. As the shell descends from the hopper it passes 



158 



DRAWING DIES 




Fig. 25. Dies Used for Drawing 3-inch Brass Shrapnel Cases 



through a locating cage A, Fig. 24, from which it is carried 
forward by a plunger B and is located on the cutting-off punch 
C. Here it is held by friction while a circular trimming tool D 
advances and trims off the surplus stock. The shell and trim- 



DRAWING A SHRAPNEL CASE 1 59 

ming are then ejected from the cutting-off punch by a sleeve E 
operated from the left-hand end of the machine, the shell being 
deposited in one box and the trimming in another; two separate 
channels are provided as shown. 

Drawing a Brass Shrapnel Case. — The dies used for drawing 
a 3-inch brass shrapnel case are illustrated in Fig. 25, as well as 
the successive operations. The shallow cup which is drawn 
from the flat blank is indicated by the heavy black line at A. 
This cup is next reduced in diameter from 4.232 inches to 3.877 
inches in the die illustrated at B. The second redrawing oper- 
ation is illustrated at C. The case is now drawn out to such a 
length that stripping pins or fingers are used to remove it from 
the punch. As will be seen, these pins are inclined and recede 
against the tension of springs as the shell passes down, and then 
engage the top edge as the punch ascends. There are six of 
these stripper pins equally spaced around the base of the die. 
The die D for the next operation is similar to the one just re- 
ferred to except that it is somewhat smaller in diameter. The 
fourth and fifth redrawing operations are done in horizontal screw 
presses because the length to which the case is drawn exceeds 
the stroke of the vertical presses. As the illustration shows the 
stripper pins in these dies are mounted in a holder having a 
spherical bearing, so that it has a limited movement in any 
direction. As the result of this universal movement, the stripper 
pins automatically adjust themselves to conform to any un- 
evenness of the edge of the drawn case; consequently, a practi- 
cally uniform pressure is exerted upon the case when it is being 
moved from the punch. The case is annealed after every draw- 
ing operation and it is reduced to an outside diameter of 3.186 
inches, and lengthened to 14! inches. All of the punches are 
tapered on the end in order to secure thicker walls near the end, 
as indicated by the illustrations. 

Multiple Drawing Die of Indexing Type. — The upper and 
lower members of a multiple drawing die for performing six 
drawing operations at one stroke of the press are shown in 
Figs. 26 and 27. The lower member, Fig. 27. contains the 
punches and is equipped with an automatic indexing mechanism 



i6o 



DRAWING DIES 




Machinery 



Fig. 26. Upper Member of Multiple Drawing Die 

which serves to carry the work around so that it is acted upon 
by the six punches and dies which successively reduce the size 
of the drawn part. Inasmuch as all of the punches and dies 
operate simultaneously, evidently a drawn piece is produced at 
each stroke of the press. Eight operations are required to com- 
plete the drawn part and their successive order is indicated in 



MULTIPLE INDEXING DIE 



161 




SECTION x-x 



Machinery 



Fig. 27. Lower Member of Multiple Drawing Die 

Fig. 28. The first operation is done in a compound blanking 
and drawing die equipped with a roll feed; the six operations 
following are performed in the automatic indexing die, which is 



162 DRAWING DIES 

shown in the accompanying illustration, and the eighth or final 
operation, which consists of turning down a flange and leveling 
the bottom, is done in another separate die. 

The automatic indexing die has a shoe A which rests on the 
bolster of the press and serves to hold six equally-spaced draw- 
ing punches B and their respective stripping collars C. These 
stripping collars are held in place by retaining ring D which also 
provides a bearing for pawl carrier E. This carrier is hardened 
and ground and has attached to it a pawl F (see plan view) and 
also two hardened pins G which engage spiral grooves formed in 
extension W of the upper member (see Fig. 26). The pawl F 




Fig. 28. Successive Drawing Operations, Six of which are done in 
Multiple Die of Automatic Indexing Type 

is normally held outward by spring H and engages hardened 
teeth / inserted in plate /. These teeth take the end-thrust of 
pawl F as the latter, with plate E, is revolved when the press ram 
ascends. Plate /, which is the index plate, has six holes into 
which are pressed the hardened bushings K. On the periphery 
of this plate there are six slots which are engaged by the end of 
locating lever L which serves to hold the plate firmly in position 
and locate the work accurately relative to the drawing dies. 
The thumb-nut M connecting with lever L is used for disen- 
gaging the lever when it is desired to turn the index plate by 
hand, in case it is necessary to remove the drawn parts. 

During one revolution of plate / each of the six holes passes 
over the clearance hole N, which is just beyond the final drawing 
die, thus allowing the drawn part to drop out of the die and into 



MULTIPLE INDEXING DIE 1 63 

a box beneath the press. The stripping collars C for the punches 
are actuated by three springs Q that are located on a circle 
underneath plate P and are held in position by three studs. 
These springs normally hold plate P upward and also collars C, 
by means of pins O. 

The steel plate T (Fig. 26) is held to punch-holder 5 by screws 
and serves as the holder for the six drawing dies Z. Between 
holder 5 and plate P a space is cored out to receive stripper 
plate U which rests upon the strippers V. (The action of this 
plate will be referred to later.) The driver W has two spiral 
grooves milled into it which engage pins G (see Fig. 27) and 
operate the pawl carrier as previously mentioned. The bolt X 
provides adjustment for this driver. The hardened rod Y 
serves to release the locating lever L on the lower member so 
that index plate I may be revolved. 

The operation of the dies is as follows : When the upper mem- 
ber descends, the successive drawing operations on the six 
parts are performed (assuming that the die is completely loaded) 
and at the same time plate E and index pawl F are turned 
backward into engagement with the next tooth J on plate I 
preparatory to indexing. The rod Y also engages the end of 
locating lever L and withdraws it from the index plate. When 
the upper member ascends the drawn parts are stripped from 
the punches and dies, and plate E, with index pawl F, is turned 
forward, thus indexing the six drawn pieces from one die to the 
next by the rotation of index plate /. When lever L is released 
by the upward movement of rod Y it drops into a notch and 
accurately locates and locks the index plate in position. This 
cycle of movements is repeated for each stroke of the press. 

In designing this die, one of the points which had to be con- 
sidered very carefully was to secure a rapid and positive strip- 
ping action for the dies in the upper members ; in fact, the drawn 
parts have to be stripped from the dies as soon as the press slide 
starts upwards so that the work will not be disarranged by 
being carried up out of the index plate. This positive stripping 
action was effected by means of plate U in conjunction with 
three levers or pawls R. These levers are pivoted to the lower 



1 64 DRAWING DIES 

member and as the upper member descends they are forced out- 
wards by three cams C\. At the end of the downward move- 
ment, levers R are in engagement with plate U, as the illustra- 
tion, Fig. 26, indicates. When the slide begins to ascend, plate 
U and the strippers V are held stationary while the dies Z move 
upward, thus ejecting the drawn parts. When the cam surface 
on lever R is engaged by cam C h it is forced outward, thus re- 
leasing plate U. In this way the strippers are actuated at the 
beginning of the upward stroke so that the drawn parts are 
pushed from the dies without leaving the index plate. As the 
slide continues to ascend the index plate is revolved into position 
for the next drawing operation. 

Dies for Rectangular Drawing. — Dies of the combination and 
double-action types are used for drawing rectangular and square 
shapes and, in some cases, special designs are employed, par- 
ticularly if the part must be drawn to considerable depth and 
only a single-acting press is available. The principal difficulty 
connected with using a single-acting press is in the arrangement 
of the blank-holder or pressure-pad on the die. A common 
method is to attach the drawing die to the ram of the press and 
support the punch below; the pressure-pad extends around the 
punch and rests upon pins which pass through the press bed and 
bear against a plate which is backed up by a rubber buffer or 
spring pressure attachment that can be adjusted to give the 
pressure required. This arrangement is satisfactory for many 
classes of work, but when drawing comparatively deep parts it 
is objectionable in that the blank-holder pressure increases as the 
die descends. Consequently, if this pressure is sufficient for the 
beginning of the drawing operation, it will be excessive at the 
end of the downward stroke. This defect is sometimes remedied 
by using extra long springs or buffers or a special compen- 
sating attachment. 

For deep drawing, when a single-acting press is to be used, a 
die equipped with a pressure-pad of the type shown in Fig. 29 
is preferred by some diemakers. The die and die-shoe rest upon 
the bolster of the press and into the latter are screwed two 
shoulder studs 5 having coarse threads onto which are fitted 



RECTANGULAR DRAWING 



165 



the handled nuts N. These nuts serve to hold down the pressure 
pad which is pivoted on one of the studs and slotted to receive 
the other so that it can be swung out of the way. (See plan 
view.) The underside of the pad is faced with a hardened tool- 
steel plate about f inch thick. When using the die, the pressure- 
pad is swung out, the blank placed in position and then the pad 
is swung back and tightened by nuts N. After a few parts have 
been drawn, the operator will be able to determine how much 




PRESSURE PAD 



PRESSURE PAD 



DRAWING DIE 




-GAGE PLATE 



! ! 



BOLSTER OF PRESS 



Machinery 



Fig. 29. Rectangular Drawing Die Equipped with Hand-operated 
Blank-holder for Use in Single-action Press 

these nuts should be tightened to prevent wrinkling. The 
heavier and more rigid the studs and pad are the less tighten- 
ing is necessary, because the object is simply to confine the metal 
before it goes into the die so that wrinkling will be impossible. 
This form of die has proved satisfactory and it is similar in 
effect to the action of the double-acting press. 

Blank-holder Pressure Compensating Attachment. — The 
principal reason why ordinary combination dies cannot draw 
as deeply as double-action dies is that the pressure between the 



1 66 DRAWING DIES 

drawing die and pressure-pad gradually increases as the part is 
drawn, as previously explained, owing to the increased com- 
pression of the drawing rubber or spring-pressure attachment. 
The result is that the stress upon the metal being drawn in- 
creases rapidly as the drawing die descends, because the stress 
due to the drawing operation is unduly increased by the ex- 
cessive pressure on the outer part of the blank. In other words, 
if the pressure upon the blank is sufficient at the beginning of 
the drawing operation, it rapidly rises as the pressure-pad or 
''drawing rubber" is compressed. On the other hand, when the 
pressure on the blank is practically uniform, as in the case of a 
double-action die, a somewhat greater depth may be obtained 
in one draw, assuming that the same material is used in each 
case and that other conditions are equal. 

In order to prevent an increase in pressure between the die 
and blank-holder, some combination dies are equipped with a 
compensating attachment. This attachment has a cross-bar 
under the table which carries the rubber pressure-pad. This 
bar extends outward at each side and vertical pins are attached 
to the ends and pass up through the press table. When the 
ram of the press descends, it begins to force these compensating 
pins downward as soon as the required blank-holder pressure is 
obtained. As the pins move downward, they also lower the cross- 
bar and rubber pressure-pad and, therefore, the blank-holder 
pressure does not increase. In other words, when there is suf- 
ficient pressure on the blank, the compensating pins are en- 
gaged by the slide and as the drawing operation continues, the 
blank-holder pressure remains practically constant, because 
the drawing rubber is carried down at the same rate as the press 
slide. The screws on the slide which engage the compensating 
pins are adjustable so that the pressure-pad can be compressed 
the required amount before the compensating attachment comes 
into action. While this attachment has been used in many 
cases where it was desired to obtain an exceptionally deep draw 
in a combination die, the results obtained have not been alto- 
gether satisfactory, because it has been found difficult to obtain 
a uniform pressure on the blank; moreover, the compensating 



RECTANGULAR DRAWING 



167 



attachment is rather cumbersome and complicates the con- 
struction. 

Combination Die for Deep Drawing. — In order to avoid the 
use of a compensating attachment, the Nelson Tool Co., Inc., of 
New York, designed a combination die that is especially adapted 
for comparatively deep drawing operations and is simple in con- 
struction. An example of the work done in this die is illustrated 
in Fig. 30, which shows the flat blank and also the rectangular 
case which is drawn in one operation. The stock is aluminum, 




Fig. 30. 



Blank and Rectangular Case Drawn from it in a 
Combination Die 



0.050 inch thick, and the case is 4! inches wide, 8 T 9 g inches long 
and is drawn to a depth of 2y§ inches. In order to draw to this 
depth in one operation in a combination die and avoid the ex- 
cessive increase in blank-holder pressure, four steel pressure 
strips A were attached to the blank-holder near the corners of 
the blank, as indicated in Fig. 31, which shows a detailed view 
of the die. These strips are the same thickness as the stock and 
they are engaged by the die during the drawing operation. 
The result is that while the blank is confined between the die 
and blank-holder, it is not subjected to an appreciable increase 
in pressure as the die descends, because the steel strips hold the 
die in a fixed position relative to the blank-holder. By this 
simple method, the increase in pressure resulting from the com- 
pression of the drawing rubber is not transmitted to the blank; 



i68 



DRAWING DIES 



the latter is merely confined between the flat surfaces of the die 
and blank-holder which are positively held a fixed distance 
apart. As the plan view to the right shows, the four pressure 
strips are so located on the blank-holder as to form a "nest" 
for the blank. 

The use of these pressure strips or distance pieces between 
the die and blank-holder not only simplifies the construction of 
the die but, in this particular instance, enables the required 
depth of 2J| inches to be drawn in one operation. At first, ex- 



-Rq 









PLAN OF BLANK-HOLDER AND DRAWING PUNCH 

Machinery 



Fig. 3i. Combination Die Used for Operation Illustrated in Fig. 30 

periments were made with pressure strips 0.012 inch thicker 
than the aluminum stock. While the results were fairly satis- 
factory, there was slight wrinkling. When strips of the same 
thickness as the stock were used, however, the aluminum cases 
were drawn without difficulty, and are a fine example of rectan- 
gular drawing. The radius of the corners of the case is yf inch, 
whereas the radius at the bottom, on the inside, is ^ inch, 
which, of course, corresponds to the radius of the drawing punch. 
The drawing edge of the die has a radius of \ inch, or five times 
the stock thickness. Located within the drawing die, there is a 
knockout which is operated by a cross-bar in the usual manner, 



RECTANGULAR DRAWING 



169 



at the upper end of the stroke. The drawing punch is provided 
with an air vent hole in the center to prevent the formation of a 
partial vacuum under the case when the latter is being stripped 
from the punch. The blanks are cut out in a separate blanking 
die. 

A die equipped with inserted corner pieces is shown in Fig. 
32. This form is sometimes used when a large number of steel 
parts have to be drawn. This construction allows the corners 
to be replaced when worn and they can be made much harder 
than if they were a part of a solid die. This design also permits 




Fig. 32. 



Rectangular Drawing Die Provided with Inserted 
Corner Pieces 



the use of expensive steel, such as high-speed steel, for these 
corner pieces. This form of die is not recommended for small 
work. The particular die illustrated was designed for drawing 
steel parts 6 by 8 inches in size and it has outworn several sets 
of corner pieces. 

Drawing Rectangular Shapes. — When making dies for draw- 
ing rectangular and square shapes, the first thing to consider is 
the form of the part to be drawn. This point is often over- 
looked by the designer, as all he may have in mind is to produce 
a box of a certain size. Therefore, he may specify a radius of 
I inch at the corner of the box when the radius could just as 
well be I inch, and perhaps the radius at the lower corner or 



170 DRAWING DIES 

edge could also be larger than is specified. This matter of 
corner and edge radius is important and may greatly affect the 
drawing operation. The kind of metal to be used should also 
be considered. It is often more profitable to make small parts 
of brass than of steel because there is less wear on the dies and 
fewer spoiled parts. When steel is necessary and the depth of 
the draw exceeds one-half the width of the box, a "deep draw- 
ing" steel should be used. A deep drawing steel which has 
proved satisfactory contains from 0.08 to 0.18 per cent carbon 
(preferably about 0.10 to 0.12 per cent); about 0.35 per cent 
manganese, with the percentage of phosphorus and sulphur less 
than 0.03 per cent. It is advisable to be on the safe side when 
deciding what thickness of metal to use; that is, it is preferable 
to use a little extra metal and have ample strength at the lower 
edge of the box, where the greatest strain from drawing occurs, 
than to use a metal that is barely strong enough to withstand 
the drawing operation. This is especially true if the part must 
be drawn to considerable depth. When using brass and alumi- 
num, the cost of the material is an important factor and it is 
common practice to begin with stock,.. .say, ^% inch thick; this 
original thickness is retained in the first draw but is reduced in 
each succeeding draw so that, when the box is finished, the sides 
will be considerably thinner than the bottom. With this 
method, less metal may be used or, in other words, a smaller 
blank than if the box were made of uniform thickness. The re- 
duction of thickness at each draw should not exceed 0.0025 inch 
on a side. Thinning the sides in this way is not considered 
practicable when using steel, owing to the comparative cheap- 
ness of steel and the increase in wear on the dies which would 
result from "ironing" or thinning the stock. 

Laying Out Rectangular Dies. — After having carefully con- 
sidered the design of the part to be drawn and the material from 
which it is to be made, the next step is that of laying out the die 
or dies, as the case may be. There are several fundamental 
points that should be considered before proceeding with the 
laying out operation. For instance, there may be some doubt 
as to the practicability of drawing a box in one operation, and 



RECTANGULAR DRAWING 171 

one might naturally suppose that by employing two operations 
many difficulties would be avoided, because the work is divided 
between two dies. There may, however, be more trouble when 
using two dies, especially if steel is to be drawn, because the 
drawing operation is confined to the corners, and forming the 
sides of the box is nothing more than a folding or bending oper- 
ation; consequently the dies wear principally in the corners and 
as the result of this wear and increase of clearance space, the 
metal thickens at the corners. In some cases the metal will 
thicken to such an extent as to make it impossible to push the 
work through the second die when two are employed, without 
rupturing the box at the corners. Moreover, when there are 
two operations, annealing may be required between the draws, 
and if this is done in an open fire oxidation takes place which 
would require a pickling operation to free the part from scale. 
Even though a closed furnace is used, the parts should be washed 
to free them from grit as otherwise the die would be lapped out 
very quickly. If there is no doubt as to whether a part should 
be drawn in one die or two, it is advisable to first make the 
finishing die and attempt to produce the part in one operation. 
If this trial draw shows that one die is not practicable, then the 
first-operation die can be made. 

The amount of clearance at the corners is another important 
point. By allowing a little more than the thickness of the 
metal between the punch and die at the corners, the pressure 
required for drawing is considerably reduced. For instance, if 
stock 0.0625 inch thick were being used, a space of about 0.067 
inch should be left at the corners; this clearance is advisable 
for a one-operation die and also for the final die of a series. The 
top surface of a first-operation die should be perfectly flat and 
smooth. If this surface is ground the grinding marks should be 
polished out as otherwise the pressure of the blank-holder will 
tend to hold certain parts of the blank more than others, caus- 
ing an uneven draw. The corners of the die, as well as the 
punch, should be made very hard. 

The radius of the drawing edge should be uniform and the 
surface smooth. The edge radius of the first drawing die (as- 



172 DRAWING DIES 

suming that more than one operation is required) is the most 
important. Theoretically, this radius should be as large as 
possible but it is restricted for the reason that the larger the 
drawing radius the sooner the blank is released from under the 
blank-holder or pressure-pad, and if this release occurs too soon, 
the metal will wrinkle; if wrinkling occurs, a fractured corner 
is liable to be the result. It is also important to make the 
corner radius as large as possible. When the corner radius does 
not exceed f inch, the radius of the drawing edge of the first die 
should be about the same as the corner radius, whereas for a 
corner radius exceeding f inch, a drawing edge radius of f inch 
should be retained. 

Determining Number of Drawing Operations. — When laying 
out rectangular dies, naturally one of the first things to con- 
sider is the number of operations required to complete the box 
or whatever part is to be drawn. The number of operations is 
governed by several factors such, for instance, as the quality of 
material, its thickness, the corner radius and also the radius at 
the bottom edge of the drawn part. In some cases, this lower 
edge can be rounded considerably, whereas in others it must be 
nearly square; obviously, when the corner is sharp a fracture at 
this point is more liable to occur owing to the pull of the draw- 
ing punch. Because of these variable conditions no definite 
rule can be given for determining the number of operations, 
although the following information will serve as a general guide. 

When drawing brass, it is safe to assume that the part can be 
drawn to a depth equal to six times the corner radius. Suppose 
a box is to be drawn that is 5 inches wide, 6 inches long and 3 
inches deep, and that the corner radius is \ inch, and the lower 
edge rounded to about \ inch radius. By applying the foregoing 
rule we find that this can be done in one operation; thus, the 
depth equals six times the corner radius, or 6 X \ = 3 inches. 
If the corners were of j inch radius, then two operations would 
be required. The larger the radius the greater the depth which 
can be obtained in the first draw. However, when the corner 
radius exceeds about h inch, the maximum depth should be 
somewhat less than six times the corner radius. A general idea 



RECTANGULAR DRAWING 



1 73 



of the maximum depths for corners of given radii may be ob- 
tained from the following figures taken from actual practice: 
With a radius of %% to ^ inch, depth of draw, 1 inch; radius 
T 3 6 to f inch, depth, i\ inch; radius f to £ inch, depth, 2 inches; 
radius \ to f inch, depth, 3 inches. 

When two dies are required the first die should have a corner 
radius equal to about five times the corner radius of the finished 
part. -The relation between the corners of the first and second 
dies is indicated by the diagram A, Fig. 33. As will be seen 
they are not laid off from the same center but so that there will 







/A 






















V 

V 


/ 








f* 






A^- 


r 
















~~V 














< 


FIRST DIE 
















< SECOND DIE 














A 




B 










Machinery 



Fig. 33. Diagrams Showing Relation Between the Corners of First- 
and Second-operation Dies for Square or Rectangular Work 

be enough surface x between the two corners to provide a draw- 
ing edge. The reason for selecting such a large corner radius for 
the first die is that when these large corners are reduced to the 
smaller radius in the second die, a large part of this compressed 
metal is forced out into the sides of the box. Now if the first 
die were laid out as indicated at B or from the same center as 
the second die, there would be a comparatively large reduction 
at the corner and, consequently, the metal would be more com- 
pressed and the drawing operation made much more difficult, 
because, as previously mentioned, the drawing action is con- 
fined to the corners when drawing rectangular work. Some- 
times dies are made as indicated at B but the reduction neces- 
sary in the second operation is liable to result in fracturing the 



174 DRAWING DIES 

metal. The radius of the first die should be laid out from a 
center that will leave a surface x (see sketch A) about § inch 
wide, although this width should be varied somewhat, depending 
upon the size of the die. 

The amount v that a rectangular part can be reduced between 
draws depends upon the corner radius and diminishes as the 
corner radius becomes smaller. For instance, a box with corners 
of I inch radius could not be reduced as much as one with 
corners of f inch radius. To obtain the total amount of re- 
duction or 2 y, multiply the corner radius required for the 
drawn box by 3; then add the product to the width and length, 
thus obtaining the width and length of the preceding die. This 
rule should only be applied when the corner radius is less than 
\ inch. For all radii above \ inch, simply multiply the constant 
0.5 by 3 in order to obtain the total reduction. Suppose a box 
is to be drawn that is 5 inches wide, 6 inches long, \ inch corner 
radius, and we desire to establish the size of the first-operation 
die. By applying the rule just given, we have \ X 3 +5 = 5§ 
inches, and \ X 3 + 6 = 6f inches. Therefore, the die should 
be made 5§ inches by 6f inches. As previously mentioned, the 
corner radius for the first-operation die should be about four 
times the corner radius of the finished part; hence the radius in 
this case would equal \ X 4 = \ inch. In this way, the number 
of operations required to draw a rectangular part are determined. 
After the drawing dies are completed, the shape of the blank 
must be determined. While a blank can be laid out which 
would be approximately the required shape, the exact form 
must be determined by trial before the blanking die can be 
made. 

Shape of Blanks for Rectangular Work. — When a rectangular 
part is to be drawn, it is common practice to cut out a trial 
blank having a width equal to the required width of the drawn 
part at the bottom plus the height of each side, and a length 
approximately equal to the length of the drawn part plus the 
height at each end. The rectangular blank thus obtained is 
beveled and rounded at the corners until by repeated trial 
"draws" the correct shape is obtained. The simple method to 



RECTANGULAR DRAWING 



175 



be described will make it possible to secure the required blank 
shape in a more direct and accurate way. It is not claimed 
that the dimensions obtained will be absolutely correct or close 
enough for the final dimensions of the blanking punch. This 
method will, however, enable the diemaker to determine quickly 
the approximate shape for the blank, and the results will be 
sufficiently accurate to eliminate many trial drawing operations, 
thus saving considerable time. 




Fig. 34- 



Diagram Illustrating Method of Determining Approximate 
Shape of Blanks for Drawn Rectangular Parts 



When laying out a blank by this method, first draw a plan 
view of the finished shell or lines representing the shape of the 
work at the bottom, the corners being given the required radius, 
as shown by the diagram A, Fig. 34. Next draw the sides and 
ends, making the length L and the width W equal to the length 
and width of the drawn part minus twice the radius r at the 
corners. We now have a blank which would produce a rec- 
tangular piece without corners. To provide just the right 



176 DRAWING DIES 

amount of material for the corners is the chief problem, which 
may readily be solved. The first step is to find what blank 
diameter would be required to draw a cylindrical shell having a 
radius r. This diameter can be obtained by the well-known 
formula D = Vd 2 -f- 4 dh, in which D = blank diameter; d = 
diameter of drawn shell; and h = height of shell. This formula 
may be expressed as a rule as follows: Multiply the diameter of 
the finished shell by the height; then multiply the product by 
4, and add the result to the square of the finished shell diameter. 
The square root of the sum thus obtained equals the blank 
diameter. After determining the diameter D (see Fig. 34) 
scribe arcs at each corner having a radius R equal to one-half of 
diameter D. The outline of the blank for the rectangular part 
is then obtained by drawing curved lines between the ends and 
the sides, as indicated by the illustration. These curves should 
touch the arcs R. The exact shape of the curve depends some- 
what upon the proportions of the drawn part but it can readily 
be determined by drawing a few trial blanks and making what- 
ever changes may be necessary to secure a more even edge 
along the top of the drawn part. 

It will be noted that the width x at the corner is considerably 
less than the width or height h at the side and, at first thought, 
one not experienced in rectangular drawing might naturally sup- 
pose that there would be insufficient metal at the corner. It 
must be remembered, however, that the stock in passing through 
the die tends to fold and wrinkle at the corners, but as there is 
insufficient space between the punch and die to prevent wrink- 
ling, the metal is packed up or upset and is forced upward, 
thus increasing the height of the corner so that the upper edge is 
about the same height as the sides and end. If the drawn part 
is quite narrow in proportion to the length, the dimensions h\ 
at the ends of the blank should be slightly less than the height 
required for the work, because the metal tends to stretch more 
at the ends, thus increasing the height. 

After laying out the trial blank, as described in the foregoing, 
and trimming or cutting the edge to conform with the outline 
obtained, the shape of the blank should be transferred to an- 



RECTANGULAR DRAWING 1 77 

other piece of the same stock. The trial blank is then drawn 
and the outline showing its shape prior to the drawing oper- 
ation serves as a record and enables the diemaker to see what 
changes in the outline should be made in order to secure a more 
even edge along the top of the drawn rectangular part. When a 
blank of the correct shape is obtained, it is used in laying out 
the blanking die. Of course, if the part must be drawn quite 
deeply, it is not feasible to secure an even edge along the top and 
the usual practice is to finish this edge by the use of trimming 
shears or a separate trimming die. 

When laying out the blank, it is often advisable not to at- 
tempt to secure a shape that will form corners that are level 
with the sides of the drawn part but rather a form of blank that 
will produce corners that are a little higher than the sides. 
This is desirable because the wear on the die is at the corners 
and when wear occurs the metal will thicken and then the 
drawn part will be low at the corners provided that no allow- 
ance were made on the blank. 

Blanks for Rectangular Flanged Shells. — When a flange is to 
be left on a drawn rectangular part, the shape of the blank may 
be determined in practically the same way as described in the 
foregoing, except that the width of the flange must be con- 
sidered. Referring to Fig. 34, the dimensions h and // x on the 
flat blank are made equal to the height of the drawn part plus 
the width w of the flange (see sketch B) ; whereas, the radius R 
at the corners should be established from the formula for a shell 
of radius r, having a flange corresponding to the width re- 
quired. The blank diameter for a cylindrical shell having a 
flange can be determined by the formula D = V^ 2 2 -j- 4 dih, in 
which D = blank diameter; d\ = diameter of the drawn shell; 
ck = diameter measured across the flange; and h = height of 
shell. After determining diameter D and the corresponding 
radius R, the outline of the blank is drawn the same as for a 
rectangular shape without the flange. 

Blank for Rectangular Tapering Shell. — If a rectangular part 
is to have tapering or slanting sides, the dimensions h and hi 
(see plan view A, Fig. 34) should be made equal to the slant 



178 DRAWING DIES 

height 5 or the height measured along the slanting surface as 
indicated by the diagram C. To determine the blank radius R 
at the corners, find the blank diameter for a tapering shell 
corresponding to the size of the corners. This diameter D — 
Vd-f -\- 2 s (d\ -\- (k), in which D = blank diameter; d\ = diam- 
eter of drawn shell at bottom; d 2 = diameter at top; and s = 
slant height. The radius R is made equal to h D and then the 
outline of the blank is drawn as previously described for a 
plain rectangular part. If the work should have slanting sides 
and a flange, the width of the flange should, of course, be 
added to the slant height and radius R established from the 
formula for a flanged tapering shell. This formula is as follows: 
D = Vdi 2 + 2 s (di + d 2 ) + dz — d-2 2 , in which D = blank diam- 
eter; d\ = diameter of drawn shell at bottom; do = diameter 
at top; dz = diameter across flange; and 5 = slant height. 

Blanks for Elliptical Shapes. — The establishing of blanks for 
drawn parts of elliptical or oval shapes requires a little more 
time than laying out the blanks for rectangular shells. In 
order to determine the outline of the blank for an elliptical 
shell, first lay out an ellipse of the same size as the bottom of 
the drawn part, as shown in Fig. 35. Then draw a rectangle 
a-b-c-d and a diagonal line a-d. Next draw from corner b a 
line b-g perpendicular to a-d; the intersection of line b-g with 
the center-line x-x locates center D, and the intersection with 
center-line y-y locates center C. Now determine what blank 
radius R would be required for a plain cylindrical shell of 
radius C-a and height //; then draw arcs having a radius R 
corresponding to the blank radius, from the centers C and G. 
In a similar manner, determine the blank radius r for a plain 
cylindrical shell of radius D-d and height //. Then draw an 
arc having a radius r and also an arc n at the opposite end. We 
now have the major or longer axis L and the minor or shorter 
axis W of the elliptical blank. The ellipse representing the 
outline of the blank is then drawn through points located by the 
well-known method, which is partially illustrated by the dotted 
lines. The method is briefly as follows: Two circles are first 
described with c as a center and W and L as diameters. A 



BLANKS FOR ELLIPTICAL SHAPES 



179 



number of radial lines are then drawn from center c, and from 
the points at which these lines intersect with the inner and 
outer circles, horizontal and vertical lines are drawn as shown. 
The intersections of these horizontal and vertical lines are points 
on the curve of the ellipse which is then traced through these 
points and represents the required outline for the blank. If an 
elliptical part is to have a flange, the blank radii R and r are 
found for round shells having a flange of whatever width may 
be required. The ellipse is then constructed the same as de- 




Fig. 35- 



Method of Determining Approximate Shape of Blanks for 
Work of Elliptical Shape 



scribed in the foregoing. Similarly, if a blank for an elliptical 
part having slanting sides is required, the blank radii R and r 
are found for tapering shells by the formula previously given. 

By following the methods described in this article, anyone 
engaged in this work should be able to lay out in a compara- 
tively short time a blank which will have approximately the 
correct shape. Of course, it is impossible to lay out a blank 
which will give an absolutely even edge along the top of the 
drawn part, because the shape will be varied more or less by the 



i8o 



DRAWING DIES 



surface condition of the dies and the physical properties of the 
metal being drawn. 

Trimming Drawn Rectangular Parts. — After a square or 
rectangular part is drawn, it is necessary to trim the edges un- 
less the depth of the draw is comparatively small, as in the case 
of can or box covers, etc. There are several ways of trimming 
the edges in a punch press. If the box is square it can be placed 
on a fixture of the type shown in Fig. 36 and be trimmed by 
cutting the four sides successively, the work being indexed by 
turning spindle B. Each cut should overlap the other by a 
small margin to insure a smooth even edge. The spindle B is 




Fig. 36. Fixture for Trimming Edges of Drawn Parts 

a running fit in the main casting A and holds the hardened 
tool-steel knife C. The dotted lines show the position of the 
box to be trimmed. As shown, a tapered wedge D which slides 
in under the lower side of the box serves to locate it and also to 
take the downward thrust of the cut. The blade or knife E, 
which is attached to the ram of the press, may be ground square 
across the end or at a slight angle on the cutting face; a slight 
amount of angle or rake is desirable when trimming thick stock. 
If the part to be trimmed is rectangular, the length of the knife 
should be equal to the length of the longest side of the box 
minus the radius of one of the corners. For instance, a box 5 



TRIMMING RECTANGULAR PARTS 



iSl 



by 6 inches having a \ inch corner radius should be trimmed 
with a knife 5^ inches long. The two long sides should be cut 
first because if the short sides were cut first, there would be a 
tendency to distort the corners. When the sides are unequal, 
the wedge D should either be double-ended or have enough taper 
to compensate for the difference in the box dimensions. 

Another method of trimming is shown in Fig. 37. In this 
case, two sides are cut simultaneously so that only one in- 
dexing is required. This method is satisfactory for soft metal 



L 




BOX TO BE TRIMMED 



Machinery 



Fig. 37- 



Form of Punch which Trims the Two Sides of Drawn 
Boxes Simultaneously 



such as brass or aluminum but is liable to cause trouble when 
trimming steel, because the corners are so hardened, as the re- 
sult of drawing, that the top corner a might split from the strain 
of the cut, unless the box were annealed for trimming. The 
fixture for indexing and supporting the work is similar to the 
form illustrated in Fig. 36. 

Points on Drawing and Forming Die Construction. — Some of 
the most common causes of trouble in the operation and con- 
struction of drawing dies will be referred to. Care should be 
taken that a shell which is the first of a series of operations is 



1 8 2 DRAWING DIES 

uniform in height all around, because a little unevenness will 
multiply as it passes through succeeding dies, thus requiring a 
larger blank than is necessary. This defect is often caused by 
the blanking ring not being concentric with the drawing die; 
the blank-holder may also bear harder on one side than on the 
other or a bad burr on one side of the blank may result in hold- 
ing that side back. If the bottom of the shell breaks out, this 
may be caused by using a die that is too small in relation to the 
blank diameter. The rule usually employed for cylindrical 
work is that a shell may be drawn to a depth equal to its diam- 
eter. Very often this depth may be exceeded somewhat but 
the strength of the bottom of the shell will be reduced for suc- 
ceeding draws. Other causes of fracture at the bottom of the 
shell are too small a drawing radius, insufficient clearance be- 
tween the punch and die, excessive blank-holder pressure, ex- 
cessive friction between the blank-holder and die, caused by 
grinding marks on either die or blank-holder, and inferior 
quality of drawing metal. 

The straight or cylindrical surface below the curved drawing 
edge of the die should not be too long because the pressure 
exerted on the metal when it is being drawn over the rounded 
edge tends to remove most of the lubrication, thus leaving very 
little for the straight surface; consequently, a scored shell is 
liable to be the result if the cylindrical part of the die is too 
long. The length of this straight part usually varies from j to 
| inch. The diameters of the punch and die should be measured 
occasionally to determine the width of the clearance space. If, 
as the result of wear, this clearance becomes excessive, the metal 
will thicken to such an extent that there will be difficulty in 
connection with succeeding drawing operations. Any taper of 
the punch in an upward direction naturally would make it 
difficult to strip the drawn part. A vent hole through the 
center of the punch and opening to the atmosphere at some 
point above the top of the shell is also very important, as it 
prevents the formation of air pockets and facilitates stripping. 
The punch should always be polished in a lengthwise direction 
as this also aids in stripping the work. 



GENERAL INFORMATION 



183 



When determining the size of the blank for an irregular or 
rectangular shape, always begin by making the blank a little 
smaller than what is expected to be the required size. Then if 
fracturing occurs, it is very evident that a larger blank cannot 
be used, whereas if the blank is oversize a fracture may occur, 
thus leading to the conclusion that the draw is not practicable, 
although a proper sized blank might be drawn without difficulty. 
The corners of a rectangular shaped punch and die should be 
very hard, because most of the wear is in the corners. Care 
should be taken that the metal does not thicken up perceptibly 
during any one draw if others are to follow, but it is advisable to 




Fig. 38. A Drawn Cylindrical Projection 

allow the corners to thicken slightly if there is only one operation 
or during the final operation of a series. To draw a cylindrical 
projection from a hole pierced in a flat blank, the hole should 
first be reamed out to prevent the lower edge a, Fig. 38, from 
splitting. This splitting at the edge when a hub is drawn 
without reaming the hole is doubtless due to the compression of 
the metal by the action of the punch, which causes splitting 
when the hole is expanded. When this compressed surface, 
however, is cut away by reaming, the stretching action does not 
have the same effect. 

In forming blanks they should always be bent with the grain 
of the metal and not across it, particularly on sharp bends. 
By the "grain" is meant the way in which the metal was drawn 
when passing through the rolls. If it is required to make bends 
at right angles to each other or approximately so, the blanks 



184 DRAWING DIES 

should be punched out diagonally across the grain. It is some- 
times found necessary to form blanks from unannealed stock, 
that is, stock which has been rolled to a certain degree of hard- 
ness. In bending this metal it springs back more or less after 
being struck in the die. This makes it necessary to make a 
more acute angle, or a smaller radius on the punch and die, than 
is required on the finished product. This difference can be 
ascertained only by the cut-and-try method. When producing 
a short bend in blanks in such a position and of such a nature 
that the blank slips away from under the punch when it is de- 
scending into the die, a spring pad is fitted into the die with the 
lower part of the bend shaped into it, and flush with the top 
surface of the die. This holds the metal securely against the 
punch in its descent into the die and insures perfect duplicates 
of the product. Where holes in a blank come near a bend, a 
strain in the metal is set up during the bending operation which 
elongates the holes. This makes it necessary sometimes to 
pierce the holes slightly oval in the opposite direction before 
forming. In testing the shape of a forming die before it is 
hardened, always apply a small amount of oil to the surface so 
that the blank will not bruise or scratch the die, which would be 
the case if the die were left dry. Never leave the inside corners 
of a die sharp when they can just as easily conform to the radius 
formed by bending the stock around the punch. This will 
strengthen the die and lessen the possibility of its cracking 
when hardened. 

When a punch or die is heated in a charcoal or a soft coal 
fire, the dust and ashes should be thoroughly scraped off the 
working portion before dipping, so that the water will have a 
free action upon the steel. Bending and forming dies, unless 
there is danger of cracking or breaking of weak parts, should be 
as hard as lire and water will make them. After hardening they 
may be warmed over a slow lire until water " sizzles " on them. 
Some toolmakers, when hardening a punch or die, apply cyanide 
of potassium to the working portions of the steel before dipping. 
They claim for this that the outer surface of the steel is rendered 
harder by the application of this caschardening substance and 



GENERAL INFORMATION 185 

thus will be better fitted to withstand the wear to which it is sub- 
jected. This practice is strongly condemned for this reason: If, 
as is often the case, the tool should fail to harden, this fact 
will be concealed by the casehardened outer coating, and the 
tool will respond to the file test as being hard whether it is 
or not. 

Gage plates should never be secured with two screws and one 
dowel-pin. It is far more practical in most cases to use one 
screw and two dowel-pins. A good method of holding gage 
plates before their exact position is determined is to clamp them 
to the die with fillister screws having washers under their heads, 
and to drill the holes in the gage plate about j } inch larger than 
the diameter of the screws, so that the gage plate may be shifted 
around. Always drill the screw holes for the gage plates through 
the die so that in case a new gage plate is required the holes will 
be spotted from the die. Whenever the gage plate comes close 
to the working portion of the die, cut the punch back far enough 
so that the body of the punch will come within f or \ inch of 
the gage plate. In making gage plates for locating large blanks 
of irregular shape, they should be made to fit the blank only at 
the point where accuracy is essential, and not to conform ex- 
actly to the irregular shape of the blank. 

When setting up a press for forming operations the blank as 
formed by the tools is used to locate the punch in the die before 
securing the die to the press. If the tools are being tried out 
for the first time and no sample has been made, they may be 
set with strips of metal cut from the stock to be formed. When 
setting the die for a piece in which the bends are not parallel 
but off at an angle, it is usually impracticable to set them with 
a previous blank, because, when the punch is brought down, the 
tendency is to push both die and blank away. The more practi- 
cal method is to locate it approximately with the blank and 
slightly tighten the screws in the press bed; then with two 
strips of metal the same size as the blank, gage the exact dis- 
tance, after which the die can be secured to the press. Do not 
assume that a die is certain to be satisfactory when the samples 
have been produced by bringing down the press slowly by hand, 



1 86 



DRAWING DIES 



as there is sometimes more or less variation in what the tools 
will do when operated by hand and when operated by power. 

"Alligator Skin" Effect on Drawn Sheet Metal. — The 
peculiar mottled effect on the drawn sheet metal cup shown in 
Fig. 39 is known in the sheet metal industry as "alligator skin." 
This marking is noticeable only when the metal is drawn or 
stretched to a considerable extent, as in the formation of a deep 
cup. There have been many reasons given for this effect. In 
producing cold-rolled strip steel, the material is annealed pre- 




Fig. 39. Illustration Showing "Alligator Skin" Effect on a Cup 
Drawn from Steel having a " Skin Hard " Surface 

vious to the last rolling operation, so as to eliminate brittleness 
as much as possible. The last rolling operation serves to 
brighten the metal and bring it to the correct thickness. For 
some work, however, it is necessary to secure a grade of sheet 
metal known as "skin hard." This cold-rolled strip steel has 
a comparatively hard surface, and, when the skin is not too deep, 
produces bright and nicely finished cold-drawn work. How- 
ever, it is much more difficult to work than the softer grades of 
steel, and is used only when a hardened surface on the material 



GENERAL INFORMATION 187 

is desired. It is when "skin hard" strip metal is being drawn 
up that the "alligator skin" effect is produced. If the metal, 
after annealing, is reduced too much in thickness in the final 
rolling operation, a hard surface is formed on the exterior which 
is much tougher than the interior; then, when the metal, in be- 
ing worked up to the desired shape, is drawn to a considerable 
extent, the interior or center portion of the cup draws much 
more than the outer surface; hence the outer surface, or hard 
skin, pulls apart, as it will not stretch anywhere near as much 
as the inside. This leaves a peculiar looking surface slightly 
depressed in those portions where the skin has broken away. 
The particular cup shown in the illustration was drawn up from 
0.037 inch sheet steel to a depth of i| inch and a diameter of 
3^ 5 g inches; the partings of the skin vary from ^g to ^ inch in 
width in those portions where the metal has broken away to the 
greatest extent. It will be noticed in looking closely at this 
illustration that the markings are much finer at certain points 
than at others. This, no doubt, was due to imperfect alignment 
of the die and punch, which caused the metal to be drawn more 
on one side than on the other. 

It might be mentioned here that this "alligator skin" effect 
very seldom appears on soft sheet steel but is quite often present 
on "skin hard" steel. Manufacturers often find that this 
"skin hard" metal comes mixed up with soft stock, indicating 
that the rolling mill is at fault in allowing too much reduction 
in the final rolling operation. 

Rubber Pressure-Pads. — The rubber pressure-pads used on 
some types of drawing dies for supplying the necessary pressure 
to the blank-holder should be built up of separate sections in- 
stead of being formed of one solid piece of rubber, proyided a 
comparatively large size is required. One advantage of the 
sectional form is that the smaller sections will not "settle" and 
lose their resiliency as soon as the large solid piece of rubber, 
because the smaller sections are of better quality. The use of 
sections also makes it convenient to build up the pressure-pad 
until the required size is obtained. The sections can also be 
utilized on different dies in many cases. 



CHAPTER IV 
BENDING AND CURLING DIES 

While it is possible, in certain cases, to bend articles during 
the operation of punching, it is usually necessary to make a 
separate operation of bending. It is sometimes possible to 
make the dies so that the various operations can be done in 
different parts of the same die-block, the piece of work being 
changed from one portion to another in order, as the various 
operations are gone through. At other times it is necessary to 
make several sets of bending dies, the number depending on the 
number of operations necessary. When a given quantity of 
work has been run through the first die, it is removed from the 
press and the next in order placed in, so continuing until the 
work has been brought to the desired shape. When a compara- 
tively small number of pieces are to be bent to a shape that 
would require a complicated and, consequently, costly die, in 
order that the bend might be made in one operation, it is some- 
times considered advisable to make two dies for the operation, 
which are more simple in form and inexpensive to make. At 
times the design of the press is such that a complicated die 
could not be used; and, consequently, dies of a simpler form, 
which can be fitted in the press, must be made. 

Simple Types of Bending Dies. — We will first consider the 
simpler forms of bending dies. The diagram A, Fig. i, repre- 
sents a die used in bending a piece of steel a to a V-shape, as at 
b. In the case of a die of this form it is necessary to provide 
an impression of the proper shape as shown; this impression, if 
the die is to be used for bending stiff stock, must be of a more 
acute angle than if stock having little tendency to spring back 
when bent to shape is used. Under ordinary circumstances the 
upper portion or punch would be made of the same angle as the 
die. It is necessary to provide guides and stops to locate the 



TYPES OF BENDING DIES 



189 



work properly. If the stock used in making the pieces is of a 
high grade and the product is a spring or similar article which 
must be hardened, it will be found necessary to cut away the 
die somewhat in the bottom of the impression, to prevent 




ZL 



\/ 





^-a,-> 


/ 













t 




SHEET STOCK 





Machinery 



Fig. 1. Simple Types of Bending Dies 

crushing or disarranging the grain of the steel to an extent that 
would cause it to break when in use. If the die is of the form 
shown at B, the width x of the punch should be slightly less 
than the width of the die minus twice the thickness of the stock. 
If possible, the upper corners d of the die should be rounded 



I0O BENDING AND CURLING DIES 

somewhat, as the stock bends much easier and with less danger 
of mutilating the surface than when the corners are sharp. 
When bending thin ductile metal the corners need but little 
rounding; if the stock is thick or very stiff, a greater amount 
of rounding is needed. 

When bending articles of certain shapes, it is necessary to 
design the tools so that certain sections of the piece will be bent 
before other portions. If an attempt were made to make the 
tools solid and do the work at one stroke of the press, the piece 
of stock would be held rigidly at certain points and it would be 
necessary to stretch the stock in order to make it conform to 
other portions of the die. In the case of articles made from soft 
stock, this might be accomplished, but the stock would be 
thinner and narrower where it stretched; however, as a rule, it 
is not advisable to do this, and dies are constructed to do away 
with this trouble. Diagram C, Fig. i, represents a die, the 
upper part of which has a plunger e that engages the stock 
first. After forcing it down into the impression, in the lower 
portion, part e recedes into the slot provided for it. The coil 
spring shown is sufficiently strong to overcome the resistance of 
the stock until it strikes the bottom of the impression; then the 
side plates / engage the outer ends of the stock and bend it, 
thus forming the article shown at g. 

Compound bending dies are used very extensively on certain 
classes of work, especially in making looped wire connections 
and articles of thin sheet stock. The sectional views E, Fig. i, 
show a die used for bending a bow spring. As the punch de- 
scends, the stock is bent down into the impression in the lower 
half and forms the stock to a circular shape. As the end of the 
punch with the stock comes into contact with the bottom of 
the impression, the punch is forced upward, the spring keeping 
it against the stock, while movable slides Ji are pressed in by 
means of the wedge-shaped pins so as to force the upper ends of 
the loop against the sides of the punch, as shown by the lower 
view. When the punch ascends, the finished loop may be 
drawn off. If the stock used is stiff it will be necessary to make 
the punch somewhat smaller than the finished size of the spring, 



TYPES OF BENDING DIES 



191 



because the latter will open out somewhat when the pressure is 
removed. 

When making looped wire work, a loop may be formed and 
the wire moved along against a stop, another loop formed, and 
so on, as indicated at D. When forming looped wire work it is 
customary to make the punch ball-shaped rather than cylindri- 
cal. The ball answers well on wire work and allows of the easy 



v ~r Yt 1 


V-H 


1 i "i~T /raw 




Ey 




M 

lnf 


JS 






N 


K 








K 








rti-U 






M^ M S'^^IW^W 



nsn: 



Machinery 



Fig. 2. Bending Die and Punch for Forming Piece shown in Fig. 3 

removal of the loop. It is sometimes desirable to close the 
upper end of an article nearly together, and if the stock used is 
extremely stiff, such as that used for bow springs made from 
tool or spring steel, it may be necessary to heat the bow (which 
has previously been bent) red hot, and finish-bend it by a special 
operation. A great variety of work may be done by modifica- 
tions of the methods for bending shown. Where but a few 



192 



BENDING AND CURLING DIES 



pieces are to be bent it is not advisable to go to the expense 
of making costly bending dies, but when the work is done in 
large quantities, such dies will produce work uniform in shape 
at a low cost. 

Blanking and bending dies are made which not only punch 
the article from the commercial sheet, but bend it to the de- 
sired shape in the same operation. As a rule, it is advisable to 
blank the article in one operation and bend it in another, but 
there are certain forms of work where it is possible to do it in a 
satisfactory manner in one operation and at a cost not exceed- 
ing that of the ordinary blanking operation. This also effects 
a saving in the cost of tools, as the special bending die is dis- 







































































X 




ar 



























































A 








B 


Mac 


Wnery 



Fig. 3. Bending Operation Performed in Die shown in Fig. 2 

pensed with. Diagram F, Fig. i, represents a punch and die 
used in punching the shoe k to the proper shape shown, whereas 
sketch G illustrates a method of producing the spherical tension 
washer shown. Gun and other irregular shaped springs are 
often punched to form by dies of this type, although, when stock 
suitable for use in making springs is employed, it will be found 
necessary to make the face of the punch somewhat different in 
shape from that desired, as the piece will straighten out more or 
less after it is punched. 

Die for Making Four Bends. — The die shown in Fig. 2 was 
designed and made for the third and last bending operation on 
the piece shown at A in Fig. 3. The metal is ^ inch thick, of 



TYPES OF BENDING DIES 193 

soft composition, and easy to bend. The first and second oper- 
ations are performed in a like number of dies, the blanking or 
cutting from strip stock being done in one die, and the bending 
of the blank to a U-shape, as shown at B, in another. No de- 
scription of these tools will be given here as they are of simple 
construction and readily understood by those who are at all 
familiar with die designing and die making. 

The tool under consideration, shown in Fig. 2, has, of neces- 
sity, several movable parts in order to make the four bends 
required to complete the work. All the members are of simple 
outline and easy to make and assemble; therefore no detailed 
description of the methods of machining each part will be given. 
The holder A is of cast iron and is machined on the bottom, top, 
and sides to receive the several steel parts. The bending slides 
B and B are located in finished seats in the holder and secured 
in place bv plates \ inch thick, each of which is, in turn, fastened 
by four T Vinch countersunk screws. The slides B have a close 
running fit, and are forced in, to make the right and left bends, 
by the cams K on the punch; their opposite or outward move- 
ments are made to take place by four compression springs C, 
located in the holder and acting against the pins D which are 
'tightly driven into slides B. The third slide E, which has 
slotted holes to allow it to move in and out a limited distance, 
begins to operate after the other two have done their work; 
the object of this latter slide is to hold the steel form F, upon 
which the work is mounted, down, and free the formed piece 
from the punch on the up-stroke. Springs hooked to the right- 
hand end of the press bolster and to pins / return the slide E 
when the ram ascends. The four steel pieces H are adjusted, 
when the die is first set up in the press, to properly locate the 
form F which holds the work. The hardened rectangular steel 
piece K forms a seat for the work. Hardened steel pieces L 
and L support the punch parts K and prevent their spreading 
when acting on the bending slides B. 

The work, having been bent U-shape previous to the finishing 
operation, is put on the former F which it pinches sufficiently to 
hold its own weight, and is carried to the die. On the down- 



194 



BENDING AND CURLING DIES 



stroke the punch parts engage the inclined faces of the bending 
slides E and force them in, causing the right and left horizontal 
bends to be made at points indicated by the dotted lines x in 
Fig. 3. Further downward movement of the press ram permits 
these two slides to move out. The cam N forces the slide E 
inward until the inner ends extend over the bending form F, 
holding it down until the final bends are made by the former M, 
and the punch ascends sufficiently to free itself of the work. 
As the press slide continues to go up, the bending slides B make 
another in-and-out movement, thereby striking the formed 
piece a second time and setting the bends. The finished part is 
removed from the form by dropping the latter into a yoke 





A 


















B 




c 




p 
















Machine ry,N. Y. 



Fig. 4. Successive Bending Operations Effected by Die shown in Fig. 5 

secured to the press in a convenient position, and giving a slight 
pull, thus stripping the work. It has been found advisable to 
taper the forms slightly from the section where the work is 
located, to the rear, to facilitate the removal of any material, 
after it is bent, that has a tendency to hug and not spring away. 
A suitable handle should be on the front end of the form, for the 
comfort and convenience of the press-man, and it should ex- 
tend to the front of the die sufficiently to make it absolutely un- 
necessary for the operator to incur any danger of accident by 
putting his hands between the working parts of the tool. The 
press in which this type of die is used is usually run at about 
100 strokes per minute, and has a slide movement of three or 
four inches. 

Die for Making Five Bends. — The making of the five bends 
in the piece shown at D in Fig. 4 was thought at one time to 
require a very expensive punch and die. Upon laying it out, 
it was found, however, that while there were a large number of 



TYPES OF BENDING DIES 



195 



parts required and various movements to be provided for, the 
punch and die would not be at all complicated, and would come 
within the limit of cost that was allowed for this operation. 
The stock from which this piece D was to be made was one- 
quarter hard brass, ^ inch wide and about 0.023 inch thick. 
The stock was received in strips of the correct width, and, pre- 
vious to bending, it was cut to required length. After the 
pieces were cut to the required length, holes were drilled and 



ife=Hi 



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E3j 



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POSITION OF PIECE AFTER BENDING 




Machinery, N. Y. 



Fig. 5. Punch and Die for Making and Bending the Part Illustrated 

in Fig. 4 

countersunk for wood-screws. As the positions of these holes 
were not always the same, it was decided to drill them instead 
of piercing them, while cutting the blanks off. 

A front elevation of the punch and die used for completing 
the bends in the piece shown at D is shown in Fig. 5. This 
punch and die was provided with two i-inch guide-posts for re- 
taining the alignment. These guide-posts are not shown in the 
illustration, but were located at the rear of the moving parts, 
so as to be out of the way of the operator. In designing this 



196 BENDING AND CURLING DIES 

punch and die the usual plan of bringing all the working parts 
to the front was observed. This facilitates the operating of the 
die and obviates the chance of the operator putting his hand 
in a dangerous position. Referring to the illustration, Fig. 5, 
A is the cast-iron body of the die, which is machined to receive 
the spring pad B and the bending slide C. The pad B, as 
shown, is actuated by a coil spring D, and is retained in its up- 
ward position by the two fillister-head screws E. This spring D 
should be weak enough, so that it will be easily compressed by 
the punch when descending into the die. The slide C for mak- 
ing the third bend is advanced by the cam F, fastened to the 
punch-holder as shown, and is retained in its backward position 
by a coil spring G, which bears against a pin G\, located in the 
base of the slide. 

Attached to the punch-holder is the punch H which forms 
the first two bends to the blank ; the third bend is accomplished 
by the slide C in the die; the fourth bend is made by the punch 
/, and the fifth bend by the punch /. The punch H slides on 
two dowels or guide pins K (one of which is shown) and works 
against a coil spring L. Two fillister-head screws M (one of 
which is shown) limit the position of this punch. The forming 
punch / slides on two dowels or guide-posts N and is operated 
by a coil spring 0. The downward movement of this punch is 
limited by two fillister-head screws, not shown. The swinging 
punch / rotates on a stud P, and is retained by a closed spring 
Q. This punch / is fastened by the stud P to the block R, 
which, in turn, is held to the punch-holder by two fillister-head 
screws, as shown. 

In operation, the strip is placed between the locating pins S 
and also between other locating pins not shown, which hold 
the blank in the correct position. Then as the ram descends, 
the punch H forces the blank down into the die on top of the 
pad B. This forms the blank into the shape shown at A in 
Fig. 4. On further movement of the ram, the cam F comes in 
contact with the slide C forcing it in and bending the blank 
over the projected part H\ of the punch H. This forms the 
blank to the shape shown at B. As the ram descends still 



TYPES OF BENDING DIES 



197 



further, the punch I bends the blank around the punch Hi, 
giving it the shape shown at C. The fifth bend is made by the 
punch /, and is accomplished as follows: As the ram still con- 
tinues in its downward movement, the punch / comes in contact 
with the block T, fastened to the die-block as shown. This 
block T rotates the punch / on the stud P, and forces the blank 
around the punch Hi. On the up-stroke of the punch-holder, 
all the slides and punches are returned to their normal position, 
the projection Hi on the punch H carrying the blank out of the 
die and leaving it in the position shown by the dotted lines 




Fig. 6. Sectional Views of Staple Bending Die 

(Fig. 5), when it is removed by hand. The forming part of the 
punch / is offset from the main body of the punch, as can be 
seen, so that the blank will slide up past it. The forming part 
Hi of the punch H is also offset, thus allowing the blank to be 
bent around it. 

All the springs in a punch and die of this description should 
be of the best quality and well tempered, so that they will not 
become fatigued to such an extent as to render any part of the 
mechanism inefficient to even a slight degree. 

Staple Bending Die. — The die shown in Fig. 6 was designed 
for bending a large number of staples that were to be made of 



198 



BENDING AND CURLING DIES 



0.025-inch sheet steel. The cast-iron punch-holder A carries 
the tool-steel punch B, which has ejector bar C running through 
its center. The outside bending dies D are provided with nests 
E for locating the blank in the required position preparatory to 





Machineri 



Fig. 7. Successive Stages in Bending Staple in Die Illustrated in Fig. 6 

bending. The staples are bent over the inside former F, which 
is riveted to the tool-steel pins G, the pins G being a sliding fit 
in the die-shoe H. 

The detail views A, B, and C, Fig. 7, illustrate steps in the 
downward stroke of the punch. At A the blank is shown in 




Fig. 8. Steel Latch which is Bent and Twisted in Die shown in Fig. 9 

position in the nest ready for the punch to descend upon it. 
Sketch B shows the punch after it has carried the blank down 
between the side bending dies and brought it into contact with 
the inside former, and at C the punch has descended a little 
further, with the result that the blank is partially bent over the 
former. At the conclusion of the downward stroke, the two 
sides of the staple will be bent into close contact with the former. 
This is the position shown in Fig. 6. 



TYPES OF BENDING DIES 



199 



On the upward stroke of the punch the inside former F rises 
with the punch until it is flush with the top surface of the die, 
this movement being actuated by the springs / that act against 
the lower side of the pins G on which the former F is mounted. 



>-.-y_ B _ L *--. C H J 




Machinery 



Fig. g. Elevation and Plan of Combination Bending and Twisting Die 

The staple is held in the punch B until the punch has almost 
reached the top of its stroke. At this point a knockout bar 
on the punch press strikes the ejector bar C and ejects the 
staple from the punch. The press is inclined so that the work 



200 



BENDING AND CURLING DIES 



drops clear of the die and leaves the latter ready for the next 
operation. 

Combination Bending and Twisting Die. — A latch for a go- 
cart is shown in Fig. 8, which was formed and twisted in the die 
shown in Fig. 9. This latch is first cut off and formed to the 
shape shown at A, Fig. 8, after which it is placed in the die and 
is bent and twisted to the required shape shown at B. The 
lower bending die A, Fig. 9, is held in a cast-iron base B, and 
pins C, driven into the former, extend down through the base 
and come in contact with a pressure plate D operated by a 
rubber pad E. The top forming die F is held by screws and 



Qd 




BLANK 



.6TL.-^"3 



N> 



o-O lO) 



-1 



Fig. 10. 



Detailed View showing how Twisting Dies K and M, Fig. 9, 
are Operated 



dowels, as shown, to the holder G, which has a shank to fit the 
hole in the ram of the press. This holder G is lined up with 
the base B by standards H, and holds two pins / which operate 
the lower twisting dies / and K. The twisting dies / and K 
correspond in shape to the dies L and M, which are provided 
with shanks and are held in the holder G by screws and 
dowels. 

The lower twisting dies J and K are given a slight upward 
movement by means of the pins /, which come in contact on 



TYPES OF BENDING DIES 201 

the downward stroke of the ram with fulcrumed levers N held 
on pins 0. These fulcrumed levers are connected to the twist- 
ing dies by pins, as shown more clearly in Fig. 10, where the 
operation of the twisting dies A' and M is illustrated. 

In operation, the blank shown at A in Fig. 8 is placed on the 
lower die A , the hole a fitting on the pin P and the blank being 
located between the pins Q. A spring plunger R, operated as 
shown in Fig. o, prevents the blank from dropping down, hold- 
ing it flush with the highest surface of the lower forming die. 
As the ram of the press descends, the upper former forces the 
blank down, bending it to the shape shown at B in Fig. 8, and 
as the ram still continues in its downward movement, the pins I 
operate the lower twisting dies through the levers N. The com- 
bined action of the upper and lower twisting dies forms both 
ends of the blank to the shape shown at B in Fig. 8. The lower 
die A, while the twisting operation is taking place, has been 
forced down to the lowest point of its travel, compressing the 
rubber pad E, which returns it to its former position when the 
ram of the press ascends. 

Compound Bending Die. — In Fig. n are shown end and side 
elevations of a die for making the two bends in the piece shown 
at B, Fig. 12, the shape of the blank previous to bending being 
shown at A . The die-bolster A is bored out to receive the two 
guide-rods B, which are made a sliding fit in the die-holder A. 
It will be noticed that the bosses on the die-holder A are made 
large, sufficient material having been left so that they could be 
bored for bushings. However, in this case it was not thought 
necessary to use bushings, inasmuch as the die was not intended 
for continuous operation. The stud or cam D held in the punch- 
holder presses on a block E, which, in turn, operates the bend- 
ing-die holder F. A hardened block G, of the same size as E, is 
held by a screw H in the die-bolster to take the thrust of the 
stud D. The stud D is made with a 45-degree angle. All of 
these parts are made of machine steel and casehardened. The 
movable member F, or die-holder, carries the die /, which, after 
the bending operations are completed, is returned to its normal 
position by the spring J, held in the bolster. 



202 



BENDING AND CURLING DIES 




E 



TYPES OF BENDING DIES 



203 



The bend a, Fig. 12, is performed with the die /, while the 
bend b is made with the punch K, which is held to the upper 
member. This punch K slides in a slot cut in the upper member, 
and is retained by a spring L against the stop M, when in its 
normal position. In operation, the piece to be bent is located 
in the lower die P in the position shown at B in Fig. 12, being 
placed against two pins c, held in the lower die. The blank is 
also additionally supported when the dies come together, by a 
pin d held in the die /. This pin is so shaped that it fits the slot 
and locates the blank properly. When the blank is located in 
the die P, the punch-holder descends, and the die / makes the 
circular bend a, which is accomplished by the stud D forcing 
the block E in the direction indicated, thus drawing down the 




Fig. 12. Blank Before and After Bending Operation 



member F, holding the bending die /. When the stud D has 
descended T 7 g inch, the holder F comes to rest, so that the blank 
is held firmly when the punch K acts on it for making the right- 
angle bend. The punch K then comes in contact with the blank 
and the adjustable block N. The block N is tapered as shown, 
and deflects the punch K inward, so that it slides in the punch- 
holder, and in its descent bends the blank at right angles. The 
block N is held to the die-bolster A by means of three screws O, 
and is adjusted inward by a tapered gib operated on by a screw 
R. Having the block N adjustable in this manner makes pro- 
vision for the blank to be bent to such shape that after the 
punch retreats it will spring back to the angle desired. The 
shank 5 is held to the punch-holder C by a screw T. A hardened 



204 



BENDING AND CURLING DIES 



block U held to the punch-holder C comes in contact with the 
holder F, and gives the final blow to the blank. 

Curling Dies for Hinges. — The dies used for making hinges 
are about as numerous in design and vary as much as the hinges 
themselves. They range from small punches and dies for 
blanking and curling in separate operations, to the complicated 
automatic machines and press attachments for producing the 



i;!:i>uii,iiul\ 



--A-T— 1 



IVi-t' 









U 



'ri 



E-q 



Machinery 



Fig. 13. Punch and Die for Curling a Hinge 

hinge complete with the two parts and pin assembled. The ex- 
act design of the die for making a hinge or, in fact, any other 
difficult piece of work cannot, of course, be determined arbi- 
trarily but must be governed by conditions. In any case, a die 
should be so designed that its first cost is not out of proportion 
to the amount saved by its use. The two dies shown in Figs. 13 



CURLING DIES 



205 



and 14 are for curling both parts of the same style of hinge and 
are simply two differently designed tools for doing the same 
kind of work. This hinge is shown in the upper right-hand 
corner of Fig. 13. The ratio of production between the two 
dies was about 5 to 7 in favor of the die shown in Fig. 14. This 
difference in output was noted while they were being used at 
different times in the same press and by the same operator, the 




B 



■psr 



1 



m 



END VIEW OF K 



in 



_^ 



^B 



T? 1 1 *P 



m 



Machinery 



Fig. 14. Hinged Curling Die with Automatic Ejector 

press being run at as high a speed as is consistent with good 
practice. 

The die shown in Fig. 13 consists of a holder or body A of cast 
iron; a slide B of tool steel (hardened, and finished by grinding) ; 
a cast-iron cap C secured to the body A by four screws and 
holding in place slide B, permitting it to have a free lateral 
movement; a spiral spring D for moving the slide outward on 
the upward stroke of the press, by pressure against pin E; a 
tool-steel die F which curls the blank, thus forming the hinge 



206 BENDING AND CURLING DIES 

joint; and a gage G for locating blanks and preventing the 
operator from pushing them too far back into the die. The 
punch consists of a holder H, a punch /, and a cam /. The 
working face of this cam is polished and made as hard as possible; 
it engages the angular end of slide B. The punch J has a small 
V-shaped groove planed in its lower face and engages the upper 
edge of the hinge blanks. When the die is in operation, the 
blank is placed between the inner end of slide B and the die F. 
When the punch descends, it forces the slide firmly but lightly 
against the side of the blank and the continued downward 
movement causes the lower edge to curl around in the circular 
pocket formed by the parts B and F. On the upward stroke, 
the slide B is pulled out to the limit of its movement by spring 
D, thus permitting the finished hinge to be removed and a new 
blank inserted. 

The second die, illustrated in Fig. 14, has a cast-iron base A 
to which die B is attached. At the rear of die B there is a 
bracket D in which the sliding shaft E is mounted. Inserted in 
the forward end of this shaft is a piece of drill rod F, the outer 
end of which is hardened and fits into the hole in the die B. 
Driven into shaft £ is a spring post G to which are hooked two 
closely coiled springs, their opposite ends being fastened to pins 
located in the bolster in such a position as to hold the springs 
at about the angle indicated by the dotted lines H and Hi. 
On the downward stroke of the punch, these springs hold shaft 
E in the position shown in the illustration. The object of the 
angular arrangement of the springs is two-fold: In the first 
place, it avoids interference between the springs and cam L on 
the punch, and, second, it minimizes the possibility of an acci- 
dent. For instance, if one spring should break, the other would 
do the work. The hinge blank is located in die B by stop-pin 
C which extends across the slot in the die. When the punch 
and die are set up in the press, it will be understood that cam 
L is below shaft E. When the punch descends, rod F is with- 
drawn by the springs in time to clear the blank before it is 
forced down and curled. On the return stroke, the shaft is 
positively advanced by contact with cam L, thus forcing it 



CURLING DIES 



207 



forward and ejecting the hinge from the die. This tool had to 
b elated in a press having the right length of stroke, to pre- 
vent the cam L from raising entirely clear of the end of shaft £ 
The ejecting device permitted a continuous feeding of the 
blanks to the die, thus increasing the output, as previously 

m Altough these dies are simple in design, there are several 
points which should be observed when constructing them. To 
Cre accurate and^utifornt^roduc^^ 




"Fig. IS- Dies for Curling tie Rims of Buckets 

the metal must be accurately made and smoothly finished. 
The curved surfaces should also be as hard as possible because 
there is considerable wear at this point, owing to the friction of 
the curling operation. When setting the die, it should be care- 
ully aligned with a punch so that when the V-groove on the 
ower side of the punch engages the upper edge of the blank, 
the latter will be held in line with the slot in the die, as other- 
It the blank will have a tendency to buckle. The stroke of 
the press should be carefully adjusted so that the punch de- 
scends just far enough to complete the curl and no more. I 
it descends too far, the work will jam the die so that it cannot 
readily be removed. It is also essential that a lubricant be 
used on the blanks to eliminate unnecessary friction in the 
curling operation. When using a die of the type shown m Fig. 
Z it is important to use blanks that have no burrs on them, 



208 



BENDING AND CURLING DIES 



(§1 



o 




fTT 777 ^, 




any 




CURLING DIES 20Q 

because the opening in the die to receive the blank should be 
only about 0.003 mcn wider than the thickness of the stock. 

Curling Dies for Tin Buckets. — In Fig. 15 are shown two ad- 
justable curling dies, such as are used for the curling, or "false 
wiring," of straight tin buckets. Dies of this style can be used 
for curling the rims of buckets of various depths, by adjusting 
the bottom of the die to the depth of the bucket to be curled. 
The die shown at A is an old design, and it was somewhat diffi- 
cult to properly adjust the bottom of this die, as one side was 
very apt to be a little higher than the other, which caused 
trouble. Because of this trouble in connection with the adjust- 
ment, a new die was made, as shown at B. The cast iron body 
a was faced off as indicated by the finishing marks /, and a 
thread cut on the inside as shown. The part b was then threaded 
to fit a, and these two parts were screwed together. They were 
then clamped to the faceplate of a lathe, and set by the finished 
surfaces / of a. The hole on the inside was then bored, and it 
was given g 1 ^ inch taper, so that the body of the bucket would 
enter with ease. The punch c was also made of cast iron, and 
finished so that it would give the desired diameter of curl. 

This die is operated in a wiring press, which has a sliding 
table. The bottom part b is screwed down to nearly the depth 
of the bucket body, just enough stock projecting above the die 
to make the curl. The amount of stock required for the curl 
can easily be found by trial. When the part b is adjusted 
(which is done by inserting a suitable wrench in the holes e), it 
is held in place by the set-screw d, which forces a threaded brass 
plug against it. At first this die was used for curling the tin 
over wire, but subsequently for double-curling, as shown at B. 
To do this, it is first necessary to make a single curl, as shown 
at m, then screw the part b in about \ inch, and repeat the 
curling operation, thus obtaining a double curl as at n. Much 
time is saved by curling buckets in this way, and they are almost 
as strong as when wire is used. 

Curling Die for Typewriter Part. — The punch and die illus- 
trated in Fig. 16 completely forms the curl in the forked lever 
shown in the upper illustration and also in position in the die 



)\Q 



lil \ I l| \». V \ l> ( I Kl I \i . I'll'. 



til / v 1'lir. piCCC !'■ Known (IS the "iil>l>.>n reverse w eight ed 
U'\ »-i " oi lln- RemillgtOO 1 \ |H'\\ i il i'i 1 1 IS 1 li»' n.n.il pi .u I It r in 
in.'. I i .i '.»••. |0 I'M in 1 tu' » in 1 ><t '.mil .i |>u-t .' in 1 \\ U 01 ItU'CC Opel 
.iluui'. 1'lw lii.( .'J >ri .i 1 i.ui ir.u.ill\ --t.ii t - - (lu' Iviul, .mil llu" 
» in I r. Iinr.lw.l in i lu- SCCMld 01 llni.l operation l>\ Ivut", U>intr.l 

around t\n arboi However, in I no present case the eve is ^'m 
pleteb lormod in one stroke ol the press in .1 vertical acting 
puin I 1 and die 

Po the base 1 oi the die are attached the othei working parts, 
the principal one being the clamp 01 jaw (< this taw is pro 
vided wiih .1 nest foi holding the piece to he operated upon 
1 1 rooks on the shatt h, the ends oi which turn m hardened and 
ground bushings • ■'. which tire provided i>» protect the base trom 
excessive weai the bushings .n*- provided with >mI holes t\s 
indicated Phe jaw is not fitted tightl) to the shaft, that is, 
the shaft is not .1 drive tit in the jaw, bu1 is fastened to it i>\ 
two -.in. ill set screws U this teature allows the jaw to be ail 
justed at v\.n 1 U the correct tingle, and also permits oi eas\ and 
ouick dismounting in case ol repairs 

When the press starts its downward movement, the pin / 
hears against the lug ; on one end oi the jaw t», causing the 
lattei to swing up m i .> a vertical position Phe pm I is secured 
in the, tool steel phmgei K b\ the set screw V< the op 

posite side oi the plunger, and hearing against an opposite tug 
.'i the jaw (i is a short phmgei 1/ actuated h\ spring A Phis 
plungei is provided foi eouali mg the pressure on G and foi 
pi e\ .'in in-', excessive torsional 01 twisting strain 

\ furthei downward rnovement oi the ram causes the ears 
.mi the phmgei to engage and boai against the front 01 outside oi 
iin' jaw and the reai oi the base, thus holding the jaw secure!) 
in the upright position and preventing it from springing back 
\ hardened and ground bearing plate of tool steel is provided in 
iiu- 1.'. n of the base, where it engages lug O, to prevent excessive 
weai Phe grooved formei a next comes in contact with the 
top of the work and starts the curl, which is finished at the end of 
the stroke Phe supporting pad (1 is depressed in the mean 
time, sliding in the block 5 On the up stroke oi the press the 



( iii'I.in*. mi,:, 



pad Is returned to Its normal position i>y the spring shown at / 
The jaw is released by the raising «>i iii« pin / and falls bai l< l»y 
gravity Into ii" position shown to the lefl 11 Is ■ * ■ • i • < I in fall 
in;' back i>y the spring U t secured to the back oJ the base and 
to 1 he stud I at i he bottom ol the \& ■■■ 

Wuiiif, I)i«:t; loi SiiiiiII Mm;;:. Cov«;rH. I ln<< loinr, ol wninj' 

dies ;i"' Biiown in Pig iy These were designed i"i curling ii" 
edges ol brass covers, bul on : ■ « • < » 1 1 1 1 1 <»i the smallness oJ the 
win- in proportion to the thickness ol iii< metal, considerable 
trouble was experienced before securing q <Ii< thai would do the 
w < ) 1 1 -. 1 1 1 < >\ ii ■ 1 1 y 'Mm- brass was 0.018 1 1 1 1 1 1 thick, ■> 1 1< 1 1 1 > 1 ■ w 1 1 i 1 1 \\ 
was 0.075 "" '' '" diameter. 1 he covers were first drawn i" the 
1 i eh 1 shape and length in single action combination dies Then 



J 




J 



>. 



Mm hi 111 1 u 



Pig 1/ 1 in.-.- i<..iiiii: .,1 Wiring Dial 

;i wiring die ( >i the design illustrated at A was made, but ii was 
not q success, as the covers appeared as shown in the enlarged 
sc< ii<<ii 'i ii<- metal, instead ol wiring .11 the top, 1 urled bach ;ii 
the point ", forming an innei shouidei To overcome this 
(liiii< nil y , the punch was bored out, as shown at B, and ;i spring 
pressure-pad inserted to prcvenl iii< bottom buckling Whih 
this undesirable feature was eliminated, buckling occurred 11 
the side •■«! the unprotected section, between ii" pad and tni 
punch, as shown at b in the enlarged section This, howevei 
gave ;i clue to the propet solution ot the problem, which was U 
bore "ui the body <>i the punch still largei and Insert a pressure 
1 Kill equal in size to the full diametei ot the inside ol the cover, as 
:,Im*wii hy ili<- right hand view C< 



CHAPTER V 

CONSTRUCTION AND USE OF SUB-PRESS DIES 

The sub-press die was originated in watch and clock factories 
for performing blanking operations requiring great accuracy, and, 
at the present time, dies built on the sub-press principle are 
employed for a great variety of work and in connection with 
many different lines of manufacturing. The sub-press is in- 
valuable not only for blanking the delicate wheels and gears of 
watch and clock movements, but for producing the numerous 
small parts, such as are required for time-recorders, electrical in- 
struments, meters, cyclometers, and a great many other similar 
devices. In fact, the extensive use of parts stamped or cut 
from sheet metal, in many delicate forms of mechanism, has 
been made possible by the sub-press, owing to the accuracy 
which can be obtained; moreover, the rapidity with which the 
parts can be produced has resulted in a great reduction in the 
cost of manufacture. As explained in Chapter I, the sub-press 
is not a type of die but rather a method of constructing dies so 
that the upper and lower members are combined in one self- 
contained unit and held in accurate alignment. The fact that 
the sub-press is a self-contained tool and is not dependent upon 
the power press in which it is used (except for motion), com- 
bined with the ease with which a sub-press can be arranged for 
use, means not only accuracy but a great saving in time, because 
in setting up the sub-press it is simply necessary to slide the 
head of the punch plunger into a T-slot of the press slide, clamp 
the base to the bed of the press, and adjust the stroke. The 
sub-press is not only a time-saver but possesses another distinct 
advantage in that the unit construction makes it unnecessary 
to align the upper and lower die members. Still another point 
in favor of the sub-press is that this construction makes it pos- 
sible to pierce smaller holes in thick stock than is possible with 



TYPICAL DESIGNS 213 

other dies, because the small punches are supported along almost 
the entire length. It is not unusual to punch holes in stock 
having a thickness which is over twice the diameter of the 
pierced hole. With sub-press dies a narrower "bridge" can also 
be left between blanks and a much better blank obtained than 
with any other form of die. The blanks are not only free from 
burrs, but always of a uniform size, the die being straight in- 
stead of having clearance, as in the case of an ordinary die 
through which the blanks must pass; therefore, the first blanks 
punched from a new sub-press die are practically exact dupli- 
cates of those obtained when the die is about worn out; obvi- 
ously, this means that a large quantity of work can be done in 
a sub-press die before it is unfit for use. 

Owing to the large number of parts of which most sub-press 
dies are composed, the first cost is, of necessity, much higher 
than that of ordinary dies, but when we consider that the sub- 
press die, if properly made, will run ten hours per day for weeks 
at a time, without grinding, the initial cost does not seem so im- 
portant. When using an ordinary follow die, it is almost 
impossible to obtain two blanks that are duplicates within very 
close limits of accuracy. One reason is that the stock to be 
punched is more or less wrinkled and does not lie flat on the 
face of the die; the result is that after the piercing punches have 
perforated the wrinkled stock and it is then flattened out, there 
is a slight variation in the distance between the holes. More- 
over, the pilot-pins on the blanking punch, that are depended 
upon to locate the stock, cannot do this with extreme accuracy, 
since they are made a little smaller than the piercing punches 
to provide clearance. On many classes of work, follow dies are 
entirely satisfactory, but when the parts to be produced are 
small and delicate, and especially when great accuracy is neces- 
sary, a die of the sub-press type should be used. 

Typical Sub-press Die Construction. — A brief description of 
a sub-press die for producing the blank shown at A, in Fig. 1, 
follows: The upper half of the casting or cylinder B is shouldered 
onto the base C, to which it is attached by screws D; it is also 
doweled in position by the two pins E. The plunger F runs in 



214 



SUB-PRESS DIES 




TYPICAL DESIGNS 215 

a casing of babbitt shown at G, the wear in which is taken up 
when necessary by screwing down the tightening nut H, which 
forces the babbitt down and in at the same time, as the cylinder 
is bored on a slight taper. The plunger has three semi-circular 
grooves milled along its length to prevent its turning. At- 
tached to the plunger is the die /, which cuts the outside of the 
blank, and the small punches J which are held in the back- 
plate K and supported by the shedder L which is backed up 
by the heavy spring M. The tension on this spring is obtained 
by screwing down screw TV which has a small hole running through 
it to allow the air to escape. The center piece O and the three 
pins P, placed between the spring and shedder, supply the ten- 
sion necessary to operate the latter. The hardened disk Q is 
pressed into the plunger behind the back-plate, as indicated, to 
take the thrust of the small punches. The base C is recessed to 
receive the base of the larger punch R which has three openings 
for the three small punches /, clearance being provided to allow 
the scrap punchings to pass through. The stripper in the lower 
member is shown at S, the resistance from the springs T doing 
the work. The most important parts are also shown in detail 
and are marked with corresponding reference letters. 

In operation the plunger descends with the ram of the press 
and the stock caught between the two flat surfaces is held firmly 
in position, thereby preventing any creeping or distortion of 
the metal during blanking. The outside of the blank and the 
pierced holes are cut simultaneously, the die being a compound 
type. Upon the return stroke of the ram, the tension from the 
small springs T forces the stripper 5 back over the punch R 
which still has the blank pressed firmly against its face by the 
shedder L, forcing the blank back into the scrap from which it 
is afterwards removed. 

Another sub-press of the common cylindrical type is shown in 
Fig. 2. To the base B is screwed and doweled the cylinder A 
lined with babbitt, as shown at C, this lining being provided 
with ribs which engage corresponding grooves in plunger D, 
which works up and down within the babbitt lining under the 
action of the ram of the press in which it is used. Nut U fur- 



2l6 



SUB-PRESS DIES 



nishes an adjustment for tightening the babbitt lining to take 
up all slack due to wear, as fast as it is developed. The die A' 
is screwed and doweled to plunger D. Accurately fitting the 
opening in this die is the shedder H, which is normally forced 
downward with its face flush with the face of the die by the 
action of spring M, which acts through the piston N and pins 0. 
A similar construction is used in the bottom member: / is 
the punch, screwed and doweled to the base; and L is the 





R 



53 



mJ 



Machinery 



Fig. 2. Sub-press Die of Typical Design 

stripper, surrounding the punch and accurately fitting it, and 
held firmly at the upper extremity of its movement by the 
pressure of suitable springs. This is restrained with its face 
flush with that of the punch, by the heads on stripper screws 
R. Thus it will be seen that the faces of the punch with its 
stripper and the die with its shedder may be ground off 
smooth and flush with each other, presenting to the eye the ap- 
pearance of two solid plates of metal, the division between the 



TYPICAL DESIGNS 



217 



fixed and spring-supported members scarcely being visible if the 
fitting has been well done. 

With this construction in mind, the enlarged details of the 
punch and die shown in Fig. 3 will be readily understood. 




Machinery 



Fig. 3. Enlarged Views of Compound Die used in Sub-press shown in 

Fig. 2 

Similar letters in each case refer to similar parts, but only the 
members of the device which actually work on the metal are 
shown. The outline of the punching made in this die is indi- 
cated by the outline of the punch and its stripper, as shown in 



2l8 SUB-PRESS DIES 

the plan view. There are two small holes c and one larger hole 
b in the blank. For punching these small holes, in addition to 
the simple arrangement shown in Fig. 2, openings in the punch 
are necessary, and small piercing punches have to be placed 
within the aperture of the die, passing through holes in the 
shedder; the holes in the punch are continued through the base 
of the sub-press, so that the waste material drops through be- 
neath the machine. The piercing punches in the upper member 
are held to die pad G by holding screws g which draw these 
parts up into their tapered seats against the shoulders formed 
on them for the purpose. The fitting at all the cutting edges is 
done with great accuracy. The punch / fits die K very closely, 
and the shedder H is also closely fitted to the die. The stripper 
L is fitted to the punch, and small punches / are accurately 
aligned and closely sized to their corresponding openings in the 
face of main punch /. The pins h are used to guide the strip 
of stock, and are pressed down by the descent of die K, return- 
ing under the action of their springs as the ram ascends. 

With the stock in place, die A', and with it small punches /, 
descends, the latter passing through the stock until they almost 
meet the corresponding cutting edges in the lower member. 
As soon as shedder H strikes the stock its motion is arrested, 
and it remains behind until the blank is cut, being meanwhile 
powerfully pressed upon the work by spring M. As the stock, 
while being sheared, is pressed down around the blank, it carries 
with it stripper L which also, by the influence of springs Q, exerts 
a heavy pressure on the stock. The whole area of metal being 
thus firmly held between plane surfaces, there is no danger of 
buckling or distortion of the stock as would otherwise be likely. 
As the ram moves upward again the blank is still firmly held on 
the stationary top of punch / by the shedder H. The stock, 
however, is carried upward with die K by stripper L, forcing the 
stock back over the punching again until the movement of the 
stripper is arrested by the heads of screws R, at the time when 
the face of the stock is flush with the top of the punching. The 
work is thus pushed back into the stock in the same position 
that it occupied before it was severed from it, and, in many 



TYPICAL DESIGNS 2I 9 

materials, when the work has been nicely done, one would 
scarcely notice that the blanks had been severed from the stock. 
This condition is taken advantage of oftentimes in clock manu- 
facturing. Gear blanks, for instance, are punched out from 
strips of metal and inserted back in their places again, minus, of 
course the stock which has been punched out to form the arms 
and the hole for the " staff " or little shaft on which it is mounted. 
These strips, thus prepared, are then taken to machines where 
the staffs are inserted and fastened, it being much easier to handle 
the little wheels in this way than if they were severed and 

handled in bulk. g , 

Besides the advantages of permanent setting of the punch and 
die and the holding of the stock to prevent distortion, which 
allows very narrow bridges of material to be left between wide 
openings, the suitability of the sub-press for delicate work, such 
as the piercing of small holes in thick stock, will be appreciated 
by reference to Fig. 3 - * will be noted that, no matter how 
small punches e and/ may be, no portion of their projecting ends 
is at any time left unsupported laterally by shedder H or by the 
work The shedder, pressing down firmly on the work, sup- 
ports the end of the punch at the point where the pressure is 
applied. It is thus possible to use a very much more slender 
punch for a given thickness of stock than can be used m ordi- 

nary dies. _ 

Sub-press Die for Blanking and Forming Copper Cups. 
The die shown in Fig. 4 was designed to blank and form up a 
copper cup or capsule used in the manufacture of balance wheels 
for watches. The copper strip is fed into the press, which then 
blanks out and draws the metal into the shape shown at R at 
the same time punching the center hole. Referring to he 
illustration, A is the base of the sub-press, B the body C the 
cap and D the plunger, all these being of cast iron machined to 
size The body and base are held together by two screws £ 
after the usual well-known manner; F is the buffer plug which 
receives the thrust of the press piston; G is the babbitt lining of 
the body B; H is the outside diameter die, held in pace by 
our screws and two dowel-pins; Hi is the outs.de diameter 



2 20 



SUB-PRESS DIES 



punch, also held in place by four screws and two dowels; / is 
the die for cutting out the center hole, and J is the punch for 
this hole. The parts H x and / also serve as forming dies in 
bringing the metal to the proper shape. The "shedders" or 
strippers A' and L are supported by four push-pins, those of the 
former resting upon springs, the tension of which is controlled 
by short threaded plugs, as shown, and those for the latter 




Fig. 4. Sub-press for Blanking, Piercing and Drawing the Copper Cup 

shown at R 

abutting against the piston M, which is pressed down by the 
large spring N, the tension of which is controlled by the plug O. 
The block P is used merely to hold the punch / firmly in place. 
The operation of the die is as follows: The press ram being at 
the top stroke, the copper strip is fed in across the top of H, and 
as the ram descends, the blank is cut from the strip by the punch 



TYPICAL DESIGNS 



221 



H\ and drawn to a cup shape between the inside edge of Hi and 
the outside edge of /. Simultaneously, the center hole is punched 
by J and /. As will be seen by referring to the illustration, / is 
made a trifle short, so that the drawing operation will have be- 
gun before this hole is punched; this prevents any distortion of 
the piece by the punch /. A little trouble was experienced with 
this tool at first, on account of the air in the hollow plunger D 
forming a cushion when it was compressed by the rising of the 
piston M, thus preventing the proper working of the die. This 
was finally obviated by making a small groove at the side of the 
piston where it worked in the plug O, and drilling a vent hole 
through as shown. This allowed free communication to the 




Fig. s. Three Forms of Sub-presses 

atmosphere, and from then on the die gave complete satis- 
faction. The variation in size among the cups, or capsules, as 
they are called, is never more than o.ooi of an inch either in 
diameter or in length. 

Large Sub-press Dies. — The sub-press construction is em- 
ployed for many large dies, as well as for those used in the pro- 
duction of small delicate work, although in their arrangement 
the larger sizes differ from those previously referred to. The 
circular type, which is commonly used for small work, is shown 
in the foreground of Fig. 5, whereas larger sizes may be seen at 
the left and rear. The die at the left has a plunger of rectangular 
shape. This operates in a bearing lined with babbitt metal, the 
same as the cylindrical form, although the bearing is not ad- 



222 



SUB-PRESS DIES 



justable. The larger sub-press seen at the rear of the small 
plunger type has a sliding head or upper die which is guided by 
four vertical posts, carefully ground and lapped to fit cast-iron 
bushings. This is a construction commonly used on heavy 
work. The same advantages that obtain in the use of smaller 





i|LiupL 



lip:;';'!" 



M 



. 



SECTION B-B 



Machinery 



Fig. 6. Sectional Die which Operates on Sub-press Principle 

sub-presses result from the larger sizes; that is, there is a sav- 
ing of time in setting up the tools; there is a greater possibility 
of punching small holes in thick stock and of leaving narrow 
bridges of metal between openings of considerable area; the 
dies, owing to their accurate and permanent alignment, may be 



SECTIONAL SUB-PRESS DIE 



223 



fitted to each other much more closely and produce parts that 
conform to the required dimensions within small limits. 

Sectional Sub-press Die. — A sectional or built-up die, which 
is built on the sub-press principle, is shown in Fig. 6 and the 
punch (which is the lower member) is illustrated in Fig. 7. 




Machinery 



Fig. 7. Punch for Die Illustrated in Fig. 6 

The plan view of the punch also indicates the irregular shape of 
the blank which is produced. The die is so constructed that 
the blanks can be changed to different shapes by simply insert- 
ing different die sections in different places of the die. At A, 
Fig. 8, is shown a modification of the blank, possible with this 
die. Another of the principal features of this sub-press sec- 



224 



SUB-PRESS DIES 



tional die is the means for stripping the scrap and ejecting, when 
it is wanted to produce punchings in quantities. The die may 
appear to be unduly light in construction, but several sets have 
been built on these lines and have given full satisfaction. Their 
light weight materially lessens the cost of handling, as well as 
the cost of making. The holder C is of good, close-grain cast 
iron planed on both sides. At the top, a recess is milled with 
an end-mill in a vertical miller. In this recess are held the 
sectional parts of the die, which are fastened to the body from 
the bottom. After having made the necessary templets, the 




o 


k\°J> 








\ G 


F 


o\ 


,w 


o 




© 




F 


m\\\ 


i H 


II II 1= 

li ii feea | i i (S=j 



II] 

ill I I 
1&!I 

" :| ll III 



-_r--_-_-_-J 

O 



Machinery 



Fig. 8. Details of Sub-press Die shown in Figs. 6 and 7 

various die sections are shaped. A few thousandths of an inch 
are left on the adjoining surfaces to permit finishing by grinding. 
The cutting edges of the die sections must be left as hard as 
possible. Die section F is shown in detail in Fig. 8. It will be 
noticed that two small holes are drilled in the center of the two 
screw holes in the piece F. This is done to enable transferring 
the screw holes to the cast-iron holder when assembling the die. 
The bottoms of the die sections are left soft in order to be able 
to drill all the screw and pin holes through the cast-iron holder 
at the same setting. Each section is reinforced on the two 
outer sides by four set-screws H, as shown in Fig. 6. In the 
center of the die a solid block I is fastened with three screws and 



SECTIONAL SUB-PRESS DIE 225 

two dowel pins. This block is hardened and ground all over to 
the shape of the templet. The ejecting or stripping device / 
for the die is made of a solid tool steel piece to the same shape 
as the templet, but is a very free fit. This part is left soft and is 
located a few thousandths of an inch more than the thickness of 
the punching below the top of the die. When the die is sharp- 
ened, the stripper is ground off the same amount. No springs 
are used with the stripper, it being actuated by two i-inch studs 
fastened with screws on the stripper. These studs pass through 
the die and holder, and are actuated by a bar fastened to the 
gate of the press, thereby forcing out the punchings from the 
die. The six punches N, Fig. 8, are upset, as shown, at the end 
where they are inserted in the holder, while the other end is 
hardened, straightened, and lapped to size. The holes for the 
punches are located after the die is finished and assembled. 

The cast-iron punch-holder K, shown in Fig. 7, is planed on 
top and bottom and across the four bosses. The four sub-press 
pins D are of tool steel, hardened as far as the head, ground to a 
light driving fit on the head end, and ground to a sliding fit in 
the die-holder on the other end. The holes for these pins were 
located so as to come in line with each other, and at the same 
time square with the punch and die. After the punch and die 
parts were hardened, they were placed together with two paral- 
lels between the castings, the punch being entered into the die, 
and the two clamped together with four C-clamps. In this way 
the holes for the four guide-posts were machined so as to be in 
accurate alignment. 

A punch part is shown at E, Fig. 8. In locating the posi- 
tions for the piercing bushings (see detail view) it some- 
times happens that the holes for the bushings are so numerous 
and small that they cannot be conveniently bored. The holes 
are then transferred by a drill that runs through the die and is 
of the same size as the piercing plug, the die being used as a 
drill jig. After drilling, the holes are counterbored to the right 
size for a driving fit for the bushings. The latter are hardened 
and ground all over, and the holes in them taper one-half degree. 
A straight dowel pin, driven in so as to be located halfway in 



226 • SUB PRESS DIES 

the bushing, and hallway in the section E, holds the bushing in 
position while in operation. A stripper plate /', Fig. 7, is placed 
over the punch sections and has a free fit on both the inside and 
outside, li is held by flat head screws which arc adjusted with 
mils from the bottom oi the holder. Between the stripper and 
the punch-shoe Q, which is made of tool steel and hardened, 
sixteen spiral springs are placed to strip the metal. The punch- 
shoes are secured to the cast iron holder K. 

Two guide pins /. for the stock, are driven into the top of 
the cast iron holder K, and two gage pins .1/ are located r\ inch 
from tht' cutting edge. A small win- is driven through the 
gage pins, In-low the stripper, having a spiral spring underneath, 
which latter is seated on the punch-shoe. When the die comes 
down, forcing down the stripper plate, the gage pins follow. 
coming np again on the upward stroke-. 

Making Sub-press Dies. The making of sub press dies re- 
quires both skill and experience, but a general idea of the method 
of procedure may be obtained from tin- following pages, as the 
principal operations connected with sub-press die construction 
are described. As the practice referred to is that of the shop 
or tool-room in which tin- die under consideration was made, 
it may not conform altogether with the methods employed 
elsewhere, although an attempt has been made to present only 
approved practice-. 

In making tin- sub press die shown in Fig. 2, the base B and 
cylinder I art- first machined and tuted together according to 
methods that would naturally In- pursued by any good me- 
chanic, kin- inner surface of tin- cylinder is grooved length- 
wise (as shown by tin- section X Y) so that the babbitt may be 

securely locked against rotary movement. Plunger D is then 
machined, and the outer surface ground ami fluted lengthwise 
with semi-circular grooves. Especial pains are taken to have 
these- grooves parallel with the axis of the plunger in both planes; 
if this is not olonc the die may In- given a slight twisting move- 
ment instead oi the perfectly straight forward one that is re- 
quired, since upon these grooves depends the angular location 
of the punch and die with relation to each other. The plunger 



MAklN<; SUB PRESS DIES 227 

is now inserted within the cylinder and, with proper precaution, 
the space between them is filled with babbitt which Hows into 
the grooves in the cylinder and those in the plunger us well, 
locking with one and guiding the other. After being cooled, 
the plunger is pumped up and down to insure a perfect bearing, 
and the nut U is screwed down until all slack is taken up. Die 
K is now made to accurately lit the tcmplei or model furnished 
the toolmaker as a sample. After ii has been completed, it is 
hardened and fastened in place. Then the model is inserted 
within it, and such holes as may be required in the blank are 
transferred to die pad G. This is done by punches with out- 
side diameters ground to fit the holes in the templet, and pro- 
vided with sharp points concentric with the outside. The pad, 
after being thus prick-punched, is put on the faceplate, the 
slight punch marks are carefully indicated, and holes are care- 
fully bored to a taper to fit the punches which are to be in- 
serted in them. The punches are finished by grinding on centers 
after they are hardened. They are supported at the shank by 
a male center, while the opposite end is temporarily ground to a 
point which revolves in a female center in the other end of the 
grinder. The punch may thus be ground all over with the 
assurance that the pointed end is true with the exterior — a 
necessary provision, as will appear later. 

It might be noted hen; that no draft is given to any of the 
cutting edges of these tools, since they do not enter each other, 
at least not to any appreciable extent, and since the stock in 
entering and leaving the cutting edges is positively moved, no 
clearance is necessary, and the die cuts practically the same 
kind of a blank throughout its life. Shedder // is fitted to die 
K and the holes for the punches are transferred to it in the same 
way as for the die pad, by means of carefully machined prick- 
punches which fit the holes in the models, these prick-punch 
marks being afterward indicated to run true on the faceplate. 
The punch is now worked out a very slight amount larger in all 
its outlines than the die. The model is laid upon il and the holes 
transferred to it, as in the case of the other parts; these holes 
are then indicated and bored out, but not ground in this case, 



228 SUB-PRESS DIES 

being left three or four thousandths of an inch smaller in diam- 
eter than finished size. The punch is fastened in place in the 
base and aligned as nearly as possible with the die. The ram is 
forced downward in a screw press until the punch enters the die 
very slightly, cutting a thin chip from its sides to bring them to 
the shape required. The punch is then worked down to this 
point all around and again entered in the die a short distance 
further, the operation being repeated until the two parts fit 
perfectly. 

In finishing the holes in the punch, after the hardening process, 
small brass plugs are first driven into each hole. The punches 
/, Fig. 3, still with their ends pointed concentric with their out- 
side surfaces, are fastened in position in the upper member, and 
the ram is brought down until these punches mark slight centers 
in the top of the brass plugs, when the ram is again raised and 
the punch J (Fig. 2) removed. The punch is then strapped to 
the faceplate and each of the small plugs is in turn indicated 
from the prick-punch marks, when it is removed and the hole is 
ground to size with a steel lap charged with diamond dust in an 
internal grinding fixture. The stripper is fitted to the punch in 
the usual manner. With the parts thus made and fitted great 
accuracy is obtainable. 

Construction of a Sub-press Die for Washers. — In order to 
avoid a complicated drawing and to set forth the principles of 
sub-press die construction in such a way that they may be 
readily understood by those not familiar with this work, the die 
used for punching an ordinary washer has been selected for an 
illustration. The general principles of sub-press dies are, of 
course, the same whether one or one hundred punches are em- 
ployed. Having selected a frame or "barrel" of the circular 
form shown in Fig. 9, it is placed in a chuck, being held by the 
upper end, and faced off on the bottom; the recess A is also 
bored to fit snugly the corresponding boss on the base of the 
press. This base is finished on both top and bottom, and the 
boss on it is turned to fit the bottom of the frame. The center 
is recessed to receive the stripper plate and blanking punch, and 
a hole is drilled completely through to allow scrap punchings 



MAKING SUB-PRESS DIES 229 

to fall to the floor. The base and frame are then fastened to- 
gether by means of bolts and dowel pins, as shown. Together 
they are clamped to the faceplate of the lathe, being centrally 
located by means of a plug center which fits into the lathe 
spindle and passes through the hole in the center of the base. 
In this position the frame is bored out to a taper of about one- 
half inch per foot. After boring, a splining tool is substituted 
for the boring tool, and with the lathe locked by means of the 
back-gears, three or four grooves B are cut the entire length of 
the bore by sliding the carriage back and forth. At the same 
setting the upper end of the frame is faced off and threaded to 
receive the cap which is screwed on the frame. After the cap 
is in place, the hole for the plunger in this cap is bored out to 
the required size. This insures the hole in the cap being central 
with the inside of the frame. 

The plunger (which is also shown in detail) is the next piece 
to receive consideration. After being centered and rough- 
turned, it is put in the center-rest, and the hole C bored and 
threaded and fitted with the button by means of which con- 
nection is made with the press slide. The internal thread in 
the plunger is carried down to a considerable depth in order to 
allow of the insertion of a tension cap, by means of which a 
sufficient tension is placed upon the stripper spring to force the 
punching back into the stock upon the return stroke of the press. 
A dog is fastened to the button and the plunger turned to fit 
the hole in the cap, great care being exercised to keep the sides 
perfectly parallel. After turning, the lathe is blocked by the 
back-gear, and three grooves E are splined, about jq inch deep, 
for the entire length. It is essential that these grooves be 
parallel with the axis of the plunger. Before the plunger is com- 
pleted, a ring, | inch wide, is made of machine steel and forced 
onto the lower end of it. The outside of this ring is trued up, 
using the plunger as an arbor, after which this end of the 
plunger is placed in the center-rest, where the ring prevents it 
from being scored or injured by the center-rest jaws. In this 
position the recess F is bored to receive the punch-holder K. 

The punch-holder is made, as are also the die stripper and 



23° 



SUB-PRESS DIES 




MAKING SUB-PRESS DIES 231 

piercing punch, by turning from a bar held in the chuck and 
finishing complete before cutting off. The recess which receives 
the head of the piercing punch should be bored at the same 
time to insure its being central with the rest of the die. The 
stripper, which is placed inside the blanking die, should be made 
of tool steel and left large to allow for grinding after hardening, 
while the hole is bored sufficiently small to allow for lapping to 
exact size. The blanking punch, which also forms the piercing 
die, is made of tool steel in the same manner, being finished com- 
pletely before it is cut off, and it is left with sufficient stock to 
grind after it has been hardened. The holes H are drilled and 
counterbored for screws to hold the punch to the base. 

After the parts are hardened, the blanking die is the first to 
be ground. It is gripped in a chuck, upper end outward, and 
the large hole / is ground out to fit the step K on the punch- 
holder. Then the hole L is ground perfectly straight and of 
the same diameter as the master templet. The top face is also 
ground off, thus completing the die. In the stripper, the hole 
M is lapped to the same dimension as that in the templet. A 
round piece of cold-rolled steel is gripped in a lathe chuck and 
turned to fit nicely this hole in the stripper. Without disturb- 
ing the chuck, wring the stripper onto this arbor and grind the 
flange or shoulder N to fit nicely the larger bore, and the smaller 
diameter to fit the smaller bore, of the die. The blanking 
punch is finished in exactly the same manner as the stripper, 
being ground to fit the recessed seat in the base. The minor 
parts, such as the stripping plate, stripper piston, pins and 
springs, are then made, and the press is ready for assembling. 

In assembling, first force the punch-holder into the seat F of 
the plunger, and then force the die onto the holder; transfer the 
holes in the die through the holder and into the plunger, and 
after they are drilled and tapped, fasten the parts together as 
shown in the sectional view of the assembled die. Remove the 
die and drill four holes in the punch-holder and plunger for the 
stripper pins O. Place the stripper piston in the plunger, above 
this the spring, and lastly screw the tension cap into place. 
The stripper pins O, which are hardened for their entire length,, 



232 SUB-PRESS DIES 

are placed in their holes in the punch-holder, and the stripper 
placed in the die, which is then secured to the punch-holder. 

The blanking punch is placed in its seat in the base and 
securely fastened by cap-screws, after which the springs shown are 
placed in position and the stripper plate drawn down by means 
of the screws P, until it is a trifle below the top of the blanking 
punch. The frame is now ready to be babbitted. Screw the 
button onto the plunger, and with a piece of oily cloth wipe the 
plunger all over, then sprinkle flake graphite onto it. The oil 
on the plunger will cause the graphite to adhere, and after the 
surplus graphite has been blown away, a thin coating will be 
left over the entire surface. The plunger is lowered inside of 
the frame until the blanking punch enters the die. In the cap 
insert the babbitting ring (shown in detail in the lower right- 
hand corner), to prevent the babbitt from flowing into the re- 
cess R, and screw the cap onto the frame. As the cap is an 
exact fit for the plunger, it therefore aligns it with the frame and 
with the blanking punch. The grooves on the plunger must be 
plugged with putty where they pass through the cap, in order 
to prevent the escape of the babbitt while pouring. A pair of 
parallels, of a height equal to the projection of the button be- 
yond the top of the cap, are now placed on the bench, and the 
die is placed in an inverted position upon them. Great care 
should be taken to avoid any vibration during pouring, as very 
little will affect the alignment of the plunger. Before pouring, 
heat the frame with a torch or jet of gas, and when the babbitt 
has attained the proper heat, which is a very dark red, pour it 
in from both sides of the die simultaneously. Allow it to remain 
until thoroughly cool, then remove the plunger, strap the frame 
to the faceplate of a lathe, and cut a spiral oil groove the entire 
length of the babbitt. 

As the blanking punch has already been ground, the next step 
is to grind the faces of the blanking die, piercing punch, and 
stripper, while all are in their proper positions in the plunger. 
They should be ground so that the face of the stripper, die, and 
punch are all flush with each other. After grinding, the parts 
should be taken from the plunger and thoroughly cleaned, so 



MAKING SUB-PRESS DIES 233 

that there will be no abrasive in the working parts. Oil all of 
the running parts in a thorough manner, then put them to- 
gether in their proper positions, and replace the plunger in the 
frame. In setting up a sub-press die, care should be taken to 
have the punch come only to the face of the die, and not enter 
it to any appreciable extent. 

Making Sub-presses at Illinois Watch Co. — As previously 
mentioned, sub-press dies are extensively used in the manu- 
facture of watches and clocks, owing to the precision and rapidity 
with which small wheels, gears, etc., can be blanked out from 
sheet stock. The general practice in the diemaking depart- 
ment of the Illinois Watch Co., in making sub-presses of the 
piston or plunger type, is as follows: 

The casting for the upper part or body of the sub-press is 
first put in a lathe with the rough barrel in the chuck, the bot- 
tom faced off, and the bottom or base hole bored out, as shown 
at A, Fig. 10. The body is next strapped, barrel outward, onto 
a faceplate, and centered by a plug which is usually a piece of 
brass driven into the center hole of the lathe spindle, and then 
turned to fit the base hole in the casting. The barrel is now 
turned on the outside and bored taper inside, the outer end or 
top being the largest. Three or four (usually three) grooves 
are next cut in the bore, as shown at B, by traversing the car- 
riage along the bed with the work held stationary. The taper 
attachment is used to guide the tool along the tapering bore. 
The piece is removed from the faceplate when it is ready for 
the next operation, which is casting the babbitt. In perform- 
ing this operation, the sub-press body is placed on the special 
base C, which just fits the bored hole in the bottom of the body. 
The piston E is then slipped into place, and is held central with 
the bore of the barrel by holes in the center of the special base 
C and in the cap D, which is next put on. It should be stated 
that in actual use the special base C fits up into the body so 
that its top covers the bottom of the bored barrel, in order to 
keep the melted babbitt where it is wanted, the base and body 
being held tightly together during the casting process, by two 
C-clamps. In taking the photograph from which this illustra- 



234 SUB-PRESS DIES 

tion was made, the body was purposely set up, as shown, in 
order to give a better view of the positions of the piston and the 
way it is held. The piston E has been previously ground per- 
fectly true from end to end and has had three grooves cut length- 
wise in it. It is also blackened with carbon, by holding it in 
.a smoky flame, before it is put into the casting jig. The babbitt, 
which is made up of tin, antimony, and a large percentage of 
copper, is now poured around the piston through the opening F 
in the cap D. Just as soon as possible, the work is cooled off 
in water — the sooner the better. The piston is now pressed 
out by means of a screw press. After being removed, the piston 




Fig. io. Sub-press Parts and Jig used for Babbitting Plunger 

is carefully lapped with a copper ring-lap and emery, and the 
grooves are also lapped until the piston can be worked in and 
out of the barrel with some degree of ease. A cap like the one 
shown at G is next fitted on so as to hold the babbitt firmly in 
place, for while the taper bore of the barrel prevents the babbitt 
from going down, it does not keep it from being pulled up. 
The body and piston are then put into a punch-press and 
" pumped" at a good rate of speed for some time in order to 
wear them in, the " spots" on the babbitt being carefully scraped 
from time to time. When worn in a sufficient amount, the 
piston is removed and carefully re-centered in a lathe, a bored 



MAKING SUB-PRESS DIES 235 

ring being used to hold it. The piston is again replaced in the 
barrel, put between centers, and the bottom and bored hole of 
the body carefully trued up. In this way any inaccuracy that 
may have resulted from the preceding operation is corrected 
and the outside of the piston, its centers, and the bore of the 
bottom of the body are made absolutely concentric. The base 
H of the sub-press is next fitted, doweled, and fastened to the 
body by two fillister-head screws. The bottom of the base is 
then trued up by taking a light cut over it, using the piston as 
a mandrel. 

The idea of making the bore of the barrel of the sub-press 
taper, is not simply to keep the babbitt from dropping down, 
as a shoulder would answer for that; but the main reason is 
that if the piston becomes loose from wear at any time, the bab- 
bitt, which has been left high on top, as shown at K, can be 
forced downward by using a ring and a powerful press, thus 
taking up the wear. The retaining ring or cap on the top of 
the barrel is not powerful enough to do this, as it is only intended 
to keep the babbitt from coming out, as stated. 

As a general rule, in fitting a punch and die into a sub-press, 
the master punch is fitted into the piston as explained, and a 
die blank, the top of which is tinned with solder, is fitted into 
the base. The punch is then brought down and an impression 
of the outline made in the solder. The die blank is then re- 
moved and drilled out as close to the lines of the impression as 
it is safe to do, after which the die is slowly and carefully worked 
out and finished, using the master punch as a guide. 

Points on Sub-press Die Construction. — In constructing sub- 
press dies it is important to have a good stand or frame, because 
upon its construction depends in no small measure the proper 
working of the die. If the stands are well made, they can be 
used indefinitely for different dies, owing to the adjustment pro- 
vided for wear. It is a disputed point whether the plunger 
should be babbitted before or after the punch and die are fitted. 
Some prefer to make the punch and die first, enter the punch 
into the die attached to the plunger, and pour the babbitt, but 
it is generally conceded that the better way is to babbitt the 



236 SUB-PRESS DIES 

plunger first; in fact, most manufacturers at the present time 
buy them already fitted up from one of the several companies 
manufacturing them for the trade. One advantage in having 
the plunger babbitted first is that it can be run continuously for 
a day or so to secure a good bearing, the cap-nut being set up 
occasionally. In this "working out," the plunger is sure to 
"creep" or change its position slightly; this is probably caused 
by the babbitt not flowing evenly and, obviously, it is much 
better for this change to take place before the alignment of the 
punch and die. In recessing the cylinder or frame to receive 
the base, the proper way is to place the plunger on the centers 
of the lathe with the cylinder attached and recess and face out on 
the bottom, using the plunger for a mandrel. With this method 
(which is applicable when the plunger is babbitted first) one has 
the assurance that the plunger is exactly central and in a ver- 
tical position with the base. 

In milling the three grooves in the plunger, it is well to space 
them unevenly, as it will then be impossible to insert it in any 
but its proper position. In locating the holes in the back-plate 
and shedder, a round master plate is usually used, thus insuring 
greater accuracy. This master plate can also be used for dupli- 
cating the die, if, at any time, this should be necessary. In 
boring the holes in the master plate, they should be made a 
trifle larger than the largest hole in the work, which gives clear- 
ance for the boring tool to pass through. When boring the 
back-plate, it should be set perfectly central with the master 
plate and then be fastened with a drop of soft solder on opposite 
sides. Having done this, a taper pin is inserted in the center 
of the faceplate of the bench lathe, and turned up on the end 
that projects, to the size of the holes in the master plate. One 
of the holes in the master plate is then wrung onto the pin, 
after which the master plate is clamped to the faceplate and 
one of the holes bored. The work is then located for boring the 
remaining holes by shifting the master plate in the usual manner. 
The holes should be left small, so as to correct the error from 
hardening, by grinding. 

When grinding, the work is placed upon the master plate in 



MAKING SUB-PRESS DIES 237 

the same manner and position as when boring, the grinding be- 
ing done by means of a steel lap several thousandths smaller 
than the hole, the enlarged end of which is charged with diamond 
dust. In separating the die from the master plate, the best way 
to remove the solder is to turn it off with a lathe tool before 
the work is removed from the faceplate. 

When making the die, great care must be exercised, as the die 
is straight and the templet must be worked through without 
any clearance; this allows an even sliding fit for the shedder. 
In case it is impossible to avoid a little clearance, it can some- 
times be corrected in the lapping operation, after hardening. 

Making a Sub-press Die of the Four-post Type. — A sub-press 
die of the four-post type is shown in Fig. 1 1 . This sub-press is 
used for making a part having rack teeth, the shape being indi- 
cated by the illustration. The punch and die are finished be- 
fore the upper and lower members are aligned with each other. 
When aligning them, the punch is entered into the die, the faces 
of the two parts being parallel with each other; then bushings 
A are slipped over the guide-posts until they rest in the bottoms 
of the cast counterbores of the die-holder B. (See upper left- 
hand sectional view.) This counterbored space has large 
pockets gouged out at the sides for the babbitt to flow into and 
form anchorages. The helical oil grooves, with which these 
posts are subsequently provided, are not yet cut, the posts 
being smooth and true as left by the grinding operation. After 
the space C is filled with babbitt, the punch and die are securely 
held in alignment with each other. The guide-posts are then 
removed and the helical grooves for oil distribution are cut in 
them. 

One of the noticeable features of this die is that the section of 
the cutting edge which shears out the rack teeth is built up of 
small segments, each containing two teeth only, these segments 
being dovetailed into the larger piece, K 5 . Each of these small 
pieces, iv 8 , is secured by two dowels which lock the parts firmly 
together. This costly and difficult construction was necessi- 
tated by the demand for accuracy in the spacing of the teeth. 
With the sectional construction shown the parts are not affected 




z o>' i ^ 



/~> 



r-<3^ 




Z®Ta 



S U. Q 



3 


'. 


! 1 


i fl 


ill 




23S 



MAKING SUB-PRESS DIES 239 

sensibly in the hardening. That piece K b may not be warped 
out of shape, it is ground to size in all its surfaces, top, bottom, 
sides, and even in the dovetail, so that when completed its plane 
surfaces are straight and parallel. The dovetail of the die 
sections A" 8 are next machined to fit the groove in K h . The 
holes in K- are then continued to pieces A" 8 , which are taken out 
and hardened, and returned to be doweled in place. It will be 
seen that this die is constructed on the sectional plan through- 
out. This makes it possible to finish most of the cutting edges 
on the surface grinder. Troubles due to distortion in harden- 
ing are thus entirely avoided. The proper end measurements 
between important points in the model are also preserved 
by leaving a slight amount of stock where two sections of the 
die come together, the parts being ground away at this point 
until the proper dimensions are obtained. 

In the few cases where the grinding wheel will not finish the 
cutting surface, extended use is made of diamond laps, these 
being in the form of steel sections of proper contour to fit the 
part of the die they are working in, these steel pieces being 
charged with diamond dust and reciprocated vertically in filing 
machines. The little dovetail in which part K 7 is inserted, for 
instance, was finished in this way. The back of the dovetail is 
perpendicular but the two sides slope somewhat from the verti- 
cal, forming a wedge-shaped opening enlarged toward the rear. 
Section K 7 is driven in from the rear, finished off, and ground 
with its front face flush with the rest of the die. 

This sub-press die is for the first operation on the blank. 
The pieces produced are afterward subjected to the action of a 
shaving die, the original blanks being left with 0.002 or 0.003 
inch stock for the purpose, which is trimmed off in the last 
operation. The punch for this first or blanking die (see lower 
view, Fig. 11) has the rack section subdivided into four parts 
only, which are matched up carefully with the sectional die just 
described. In the shaving die, however, this punch is built in 
sectional form as described above for the blanking die, so that 
great refinement in measurements is secured. 

A feature of the shaving die, to which reference has been made, 



140 



SUB PRESS DIES 



is the use of a "nest'' to locate the work. In this trimming 
operation the punch is in the upper member and the die in the 
lower one. On the surface of the die, which is similar in con 
struction to the one shown in Fig. i.\ are placed steel guiding 
plates, / i and / '■•. which form the nest referred to. I'lnw have 
their edges shaped to the outline of the piece to be operated 
upon and are pressed inward by flat springs II at the outer edge, 




Fig. ia« Shaving Die with N<-st for Locating Work Detailed Views 
Illustrating Action oi Locating Plates 

being allowed a slight lateral movement although prevented 
from being displaced by shoulder screws I . 1'hc holes through 
which these screws pass are slotted to permit this; the end of 
the slot limits the inward movement of thr plate. As shown in 
the enlarged views, .1 and B, the inner edges oi these plates are 

beveled backward SO as to form a reeess in which the work may 

he located. The descent oi the punch forces out the plaits (as 
at B) which, as they are displaced, still guide the work so that 



MA k INC SUB PRESS DIES 



' I I 



it is properly centered over the die. These beveled edges oi the 
plates have I li<- further advantage oi curling the chip oul oJ I li<- 
way where ii does not <l<\)', the i < >« >i and may be easily cleaned 
oil. The shedder //, which tonic:; up from below and removes 
the work, < lost:, the lower opening eHe< tively so thai ili<" whole 
device is ( lu'i> tighl , 

Even greater accuracy is advisable in the fitting <>i the punch 
and die in this shaving sub-press than is necessan in the one 




Pig, 1,1. Sui) prsn Dio Equlppod with Sooondarji Snockoul Pin ''■ 

used lor blanking only, ii ii is desired to produce clean woil 
free from burrs. The necessity foi this will be apprei iatec] upoi 
examining detailed section />, which shows in magnified forn 
ilu- action oJ Hi*' cutting edges, n the punch does nol mate! 
up closely wiili the edge oJ die A, the stock is bent upward 
leaving a sharp burr, while the punch impresses the outline <> 
its cutting edge on ill* - i<»i> surface of the blank. 



24: 



SUB-PRESS 1)1 KS 



Stripping Blanks that Adhere to Punches and Ejectors. — 
Every diemaker or press hand is familiar with the troublesome, 

disastrous effect oi having drawn and blanked pieces cling long 
enough to the ejector, or knockout, for the punch to descend 
upon a new piece of stock and also the punching just made. 
The outcome is likely to be a broken die. When using a sub- 
press die similar to that shown in Fig. 13, which is for blanking 
and drawing shallow cups, many thousand cups may be drawn 




Machinery 



Fig. 14. Machine for Separating Blanks from Stock which has passed 
through Sub-press Dies 

without any mishap, especially if little or no oil is used on the 
stock, but without oil the life of the drawing die is shortened, or 
if copper or brass is being drawn, the metal tends to amalgamate 
with the die which, at intervals, must be taken down in order 
to remove this amalgamated material. On the other hand, if. 
enough oil is put onto the stock to keep the dies in good con- 
dition, the cups or blanks may adhere to the face of the knock- 
out long enough to cause trouble. The simple device shown in 



SEPARATING BLANKS FROM SCRAP 243 

Fig. 13 will prevent difficulty from this cause. The cast-iron 
plunger A carries the hardened drawing die B into which the 
knockout C is inserted for pushing the drawn piece from the die. 
If the cup D should cling to the face of the knockout by oil 
contact, the secondary knockout pin E, operated by a tlat spring 
(see enlarged view) , would force the work away from the face of 
the knockout as soon as the cup was pushed out of the drawing 
die. As spring F is strong enough to break any oil contact, the 
work is caused to drop immediately and the result is that the 
die can be operated at a much higher speed. The particular 
cup shown is if inch in diameter, £ inch high, and 0.02 inch 
thick. 

Separating Sub-press Die Blanks from Scrap. — When flat 
blanks are cut in compound sub-press dies, the blanks are 
pushed back into the openings from which they were cut by the 
action of the stripper, and if the stock is much over 0.02 inch 
thick, considerable trouble is sometimes experienced in removing 
the blanks. Fig. 14 shows a machine that is used for forcing 
the blanks from the strip of stock without marring them. This 
machine is equipped with a soft rubber wheel A which, as the 
illustration shows, is supported on the sides by steel flanges 
which are quite large in diameter in proportion to the diameter 
of the wheel. The table of the machine is formed by a knee 
or angle iron which is provided with adjustable guides, and 
is recessed to receive bushings B having different sized holes. 
Before using this machine, a bushing is inserted in the table 
having a hole somewhat larger in diameter than the diameter 
of the blanks to be forced out of the stock. The guides are 
then adjusted to allow the strip to slide through freely, after 
which the table is raised until the rubber wheel bears against 
the stock with a slight pressure. The wheel is then rotated by 
power, and it is simply necessary to place the end of the strip 
under the wheel which will then automatically feed it along, at 
the same time forcing out the blanks through the hole in the 
bushing. The diagram at the right illustrates how the blanks 
are fed out of the scrap as they pass between the bushing and 
the rubber wheel. 



CHAPTER VI 
SECTIONAL PUNCH AND DIE CONSTRUCTION 

Many dies at the present time are formed of sections instead 
of being cut out of a solid piece of steel. This sectional con- 
struction is employed more particularly for large dies, especially 
when the form is complicated. There are two principal reasons 
for using the "split" or sectional die. One is that it some- 
times happens that the blanks to be cut are of such a shape that 
the die can be more quickly and cheaply made by making a 
split die than by making a solid or one-piece die. The other 
reason is that when the required blank must be of accurate 
dimensions, and there is a chance of the solid die warping out of 
shape in hardening, the split die is preferred, because it can be 
much more easily ground or lapped to shape; moreover, a solid 
die is liable to be cracked by the hardening process, and in the 
case of a large die of complicated form this, of course, means a 
considerable loss. Some dies are also provided with one or 
more sections, at points on the die-face where the work is severe, 
so that the die can easily be repaired by simply replacing these 
sections when they have been worn excessively. 

Examples of Sectional Die Construction. — Fig. i shows the 
manner in which the ordinary split die is sometimes made. 
After the die is worked out, it is hardened and ground on the 
top and bottom. The two sides A are then ground at right 
angles to the bottom. The cutting parts of the die, B, are 
next ground at an angle of ij degree to the bottom, so as to 
give the necessary clearance in order that the blanks may 
readily drop through. The key D is now set in place, and the 
die is keyed in the die-bed by the aid of a taper key. The key D 
prevents the die from shifting endwise ; the keyway should have 
rounded corners as shown, which not only give added strength, 

but also act as a preventive to cracking in hardening. The 

244 



SECTIONAL DIE DESIGNS 245 

last operation on this particular form of die is to grind the two 
circular holes. This is done by first lightly driving two pieces 
of brass or steel rod into the holes until they are flush with 
the face of the die. The exact centers are then laid out and 
spotted with a prick-punch, care being taken to get the centers 
central with the sides B. The die is now fastened to the face- 
plate of a universal grinder, and the center mark is trued up 
with a test indicator until it runs exactly true. The brass 
piece is then driven out, and the hole ground to size, with i| de- 
gree taper for clearance. The other hole is next ground out in 
a similar manner, which completes the operations so far as the 



U 



O 



%/ 




THE BLANK Machinery 



Fig. 1. Simple Example of Sectional Die Construction 

die is concerned. It often happens with a die of this kind that 
when it is placed in the die-bed and the key driven in place, it 
will "close in." To overcome this, the die is relieved after the 
manner shown at C, which does not in any way prevent it from 
being securely held in place when in use. 

Fig. 2 shows a rather novel form of split die; this die with a 
slight change practically takes the place of two dies. It is used 
for piercing slots in brass plates. The size of the slot for one 
style of plate is 4§ inches long by \ inch wide; for the other 
plate the slot is 4 inches long by j$ inch wide. The cutting part 
of the die is made in four sections, A, B, C, D. When cutting 
the 4§-inch plates, sections C and D are used, whereas, when 
cutting 4-inch plates, sections E and F are inserted between 
the parts A and B. The soft steel bushings G (through which 



246 



SECTIONAL DIES 



dowel-pins are inserted) are used to allow for the contortion of 
the parts A and B in hardening. It may be added that the 
four bushings shown in the piece A were driven in first; then 
solid pieces were driven in the part B; then the holes were 
drilled in these latter pieces, being transferred from the bush- 
ings in the part A . The sections C, D, E, and F are hardened 
only at the cutting ends. 

The dies shown at A and B, in Fig. 3, illustrate how the 
sectional construction may facilitate making the die and also 
lessen the danger of spoiling it in hardening. The punch for 
die A was made before the die. This punch consists of a cast- 
iron holder to which is attached a steel plate forming the punch 




Machinery 



Fig. 2. 



Sectional Die having Interchangeable Parts so that Two Sizes of 
Blanks can be Punched by Changing the Central Pieces 



proper. After the punch was hardened and attached to the 
holder by screws and dowel-pins, the outside was ground to the 
required diameter; then the die was machined and, after harden- 
ing, ground to tit the diameter of the punch. The sections a 
and b were then fitted to the die and fastened with screws and 
dowel-pins, as shown. The cutting edges of these sections were 
then sheared to the required form by means of the punch. As 
these inserted parts were small they did not change to any ap- 
preciable extent in hardening. The punch for the die shown at 
B was also made first. After hardening it and grinding the 
circular part, the die was ground at c to fit the punch. The 
sections d were then fitted to the die and the cutting edges 
sheared by the punch. In hardening these sections, one of 



SECTIONAL DIE DESIGNS 



247 



them changed so much at the point e that it had to be discarded 
and another one made. This did not require any great amount 
of work, however, but if the die had been solid, obviously, it 
would have been entirely spoiled. 

Sectional Die for Square Washers. — The sectional die shown 
in Fig. 4 is so designed that all the cutting edges and the inside 
of the die can be machined and ground to the required dimen- 
sions without requiring any hand work. This construction 
makes the punch and die inexpensive to produce, and in event 
of its being damaged during the hardening process or when 
placed in operation, the damaged parts can be renewed at a 







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Fig. 3. Examples Illustrating Advantages of Sectional Die Construction 

relatively small cost. The punch and die are used in manu- 
facturing laminated copper washers in large numbers. These 
washers are square and have a square hole in the center; they 
are produced from sheet copper 0.020 inch in thickness. An in- 
clined power press with automatic roll feed is used, and the 
finished work slides into a receptacle at the rear of the press. 

By referring to the plan and sectional views of the die, it will 
be seen that there are three piercing and three blanking dies 
carried on one bolster. The die is made up of fifteen sections 
which are held together by double dovetail plugs fitting into cor- 
responding holes. When ribbon stock is fed through the die, 
the holes in three washers are pierced at the first stroke of the 
ram, and at the next stroke the blanking punch cuts away three 



248 



SECTIONAL DIES 



washers with the holes in their centers which were produced by 
the preceding stroke; at the same stroke, the holes are pierced 
for the next three washers. The diagram, Fig. 5, shows the 
order of the piercing and blanking operations. None of the 
sections of the die have been drawn in detail as they will be 
readily understood from the assembly drawing. All of the die 




SECTION X-X 



SECTION Y-Y 



Machinery 



Fig. 4. Blanking and Piercing Die of Sectional Construction 

sections are machined approximately to the required dimensions 
with the exception of the inside or cutting edges, which were 
left a few thousandths over size to permit grinding them after 
hardening. The face is recessed on the outer edge to within 
\ inch of the cutting edge and f inch from the bottom, thus 



SECTIONAL DIE DESIGNS 



249 




leaving a narrow strip all around the cutting edge in order to 
reduce as far as possible the surface to be ground. 

Each section of the die is held securely to the cast-iron bolster 
D with one or two fillister screws, and the sections are then 
wedged together with double 
dovetail blocks C. The cut- 
ting edge of each section is 
hardened down only about 
f inch and is drawn to a 
light straw color. When 
all the sections are assem- 
bled on the bolster D, the 
double dovetail holes are 
laid out with a templet and 
each of the sections is then 
milled with a dovetail cut- 
ter to receive the clamping 
blocks C. The blocks are 
made of tool steel, in strips 
12 inches long; these strips 
are then sawed up into 
pieces f inch in length and the ends are filed to a slight taper 
so that they will just enter the holes between the die sections. 
These blocks are hardened in oil and drawn to a blue color. 
The die sections are next screwed to the bolster and the dove- 
tail wedges are driven in. This method of fastening holds the 
die as securely as if it were a single piece. 

Each of the piercing and punching dies is equipped with an 
ejector plate E which is a sliding fit in the holes and held in 
position with four flat-head screws F. Spiral springs are placed 
around these screws to hold the ejector plates in position. The 
screws F extend through the bolster and carry adjusting nuts G 
which fit in counterbored holes in the under side of the bolster. 
Small holes are drilled in the under side of the bolster, before 
the counterbored holes for the adjusting nuts are bored. These 
small holes are then plugged up to keep the drill from running 
out while counterboring the larger holes for the nuts G. When 



Fig. 5. Diagram Illustrating Piercing and 
Blanking Operations Performed in Die 
shown in Fig. 4 



250 



SECTIONAL DIES 



the plugs are removed from the small holes, the portion of the 
hole which was not removed during the counterboring operation 
serves as a guide in drilling a hole to receive the small pin H 
which is tapped into the nut G and keeps it from turning. The 
ejectors are adjusted by means of the screws F so that they are 




SECTION X-X 



SECTION Y-Y 



Machinery 



Fig. 6. Plan and Sectional View of Blanking and Piercing Punch for 
Die shown in Fig. 4 

about ^ inch above the cutting edge of the dies. A long guide 
plate / is placed at each side of the die and fastened in position 
with fillister screws and a dowel-pin on each end. 

The cast-iron bolster plate D is planed on the bottom and top 
and also across the bosses. The four holes in each corner are 
next drilled, reamed, and counterbored to receive the sub-press 



SECTIONAL DIE DESIGNS 25 1 

pins /, similar holes being made in the punch-holder after the 
punch and die have been assembled. The sub-press pins / are 
made of tool steel hardened up to the head; the heads are 
ground to a driving fit in the die-bolster and the pins are ground 
to a sliding fit in the punch-holder. To locate the holes for 
these pins in line with each other, and also to have them square 
with the punch and die, the following method was used: After 
the punch and die were hardened and assembled, two parallels 
were placed between the bolsters. The punch was placed in- 
side the die and the punch and die clamped together with four 
C-clamps. After the work had been clamped in this way the 
holes were bored in the punch-holder through the holes in the 
die-bolster, and were consequently in perfect alignment. ^ 

Fig. 6 shows plan and sectional views of the blanking and 
piercing punches A and B, which are made of tool steel and left 
soft. These punches are secured to the cast-iron holder C by 
means of two fillister screws and two dowel-pins. In order to 
locate the punches in proper alignment with the die, the punches 
are first marked so that they can be replaced in the same posi- 
tions. The ejectors are then taken out of the die, and blocks 
made of f-inch cold-rolled steel are placed in the die holes in 
their places. These parallel blocks are faced off to the proper 
height to bring them T V inch below the cutting edge, all six of 
the blocks being of the same height. The punches are next 
placed in their respective die holes and the punch-holder C is 
then slipped over the four sub-press pins in the die-bolster and 
lowered onto the punches. With a right-angle scratch-awl, lines 
are marked on the punch-holder to locate the four sides of each 
punch, the scriber being worked through the screw holes in the 
die-bolster. The punch-holder is next withdrawn, and from the 
outlines of the punches on the holder the four holes for each 
punch are located, drilled, and counterbored to receive the two 
set-screws and the two dowel-pins. When all of these holes are 
drilled in the holder, the latter is once more replaced on the 
punches and secured with four C-clamps. Care must be taken 
not to twist the punches and also to see that the two bolsters 
are parallel with each other. All of the screw and dowel-pin 



252 SECTIONAL DIES 

holes are now drilled into the punches to a depth of about 
■g 1 ^ inch, the holes in the punch-holder serving as a guide. The 
C-clamps are now loosened and the punch-holder removed; all 
of the punches are then taken out of the die and the holes are 
drilled to the required depth, after which the screw holes are 
tapped. When this work has been finished, the punches are 
replaced in their respective positions on top of the blocks in the 
die. Care must be taken to have all the chips removed and the 
work perfectly clean. The punches are secured with screws and 
the two bolsters again strapped together with four C-clamps; 
straight dowel-pin holes are then reamed through the bolster 
into the punches. In this way all of the punches and sub-press 
pins are in perfect alignment. 

Pilots D are screwed on top of the three blanking punches to 
guide the metal during the blanking operation. These pilots 
enter the holes in the washers which were pierced by the pre- 
ceding stroke of the ram, and prevent the work from twisting. 
The pilots are held in place by a screw and a dowel-pin. A 
stripper plate E made of T 5 g -inch cold-rolled steel surrounds the 
punches and is held in position by the tension of fifteen springs. 
This stripper plate is made to fit between the guides / (Fig. 4) 
on the die and is a free fit on the outside of the punches. The 
stripper plate is adjusted by the flat-headed screws and nuts 
F. It will be noticed that there is a small hole in the center of 
each spiral spring seat. These holes are made in the following 
manner: All of the holes in the stripper plate are laid out in 
the usual way and drilled through with a |-inch drill; the 
stripper is then placed on the bolster with all of the punches in 
position and the holes are transferred through onto the bolster. 
The spring seats can now be counterbored on the stripper and 
bolster and by this means all of the spring seats will be in perfect 
alignment with each other. 

Sectional Die for Linotype Type-bar Plates. — A punch and 
die for producing the type-bar plates for linotype machines is 
illustrated in Fig. 7. These plates have one hundred rectangular 
holes 0.060 by 0.360 inch in size, and the bar is 0.03 inch thick. 
One of these plates is attached to the under side of each linotype 




253 



254 SECTIONAL DIES 

machine for holding the end springs which return the type bars 
after the keys are struck by the operator. It is necessary to 
have these type-bar plates made with considerable accuracy; 
the holes must be of the size specified, there must be the proper 
space between them, and their sides must be parallel and per- 
pendicular, respectively, with the edges of the plate. Evidently 
these conditions would make it very difficult, if not impossible, 
to produce plates of this type with a single punch and die and 
a suitable form of spacing mechanism. 

Several attempts were made to produce a punch and die for 
this purpose before a successful device was hit upon. In the 
first case, the punch and die appeared to be satisfactory after 
it was finished, but had only run a few days when one of the 
bridges caved in to such an extent that attempts to repair it 
were unsuccessful. The second punch and die was of similar 
design to the first, except that special means were taken to 
strengthen its construction. When this die was inspected after 
hardening, however, it was found that two of the bridges were 
cracked in the corners. It was then decided to make a sectional 
form of punch and die which would enable individual parts to be 
replaced when broken or worn in service, without necessitating 
the construction of an entirely new tool. The die section 
adopted for this purpose is indicated at B in Fig. 9. It will be 
seen that two -j 5 g-inch holes are drilled and reamed through 
these sections, pieces of drill rod being used to hold the sections 
together in a 30-degree bolster; the sections were wedged in this 
bolster by means of a suitable gib and set-screws. This die also 
proved a failure because no provision had been made for guide- 
posts or pilots. The result of this omission caused the die to 
shift while in service, so that the punches were stripped to such 
an extent that they became absolutely useless. The difficulties 
met with in early forms of dies for producing these type-bar 
plates are mentioned in order that the same trouble may be 
avoided by other shops that are called upon to produce punches 
and dies of this type for similar classes of work. 

Fig. 7 represents the form of sectional die which was finally 
developed for this operation. All parts of this tool which are 



256 SECTIONAL DIES 

likely to be worn or damaged in operation are made inter- 
changeable, duplicate parts being kept in stock so that they can 
be placed in service when required. The die pieces are machined 
to the required dimensions, allowing 0.005 inch for grinding and 
lapping. One of the die sections C is shown in Fig. 9. In 
order to machine these parts so that the slot would be the same 
distance from the inclined sides of the bolster, the milling fixture 
(also illustrated in Fig. 9) was designed for producing them. 
The cast-iron block of this fixture is held in an ordinary milling 
machine vise and the pins E and F arc so placed that the blank 
for the die sections will be held at an angle of 60 degrees. The 
strap G holds the work in position while milling; all of the 
pieces are first milled at one end to an angle of 30 degrees, after 
which they are turned over in the fixture to have their opposite 
ends milled in a similar manner. Before starting the section 
milling operation, the machine is set to produce pieces of the re- 
quired length, and it will be evident that this method of pro- 
duction insures having all the die sections of exactly the same 
size. The same fixture is used for milling the slot in the die 
section; for this purpose the fixture is swung around 30 degrees 
and a cutter 0.360 inch wide is used, the slot being cut 0.060 
inch deep. The three sides of the slot are now relieved with a 
file and after being hardened and drawn to a light straw color, 
the sections are ground on both sides so that the section through 
the slot will just enter the 0.060-inch space in the gage H, and 
the thicker section will enter the 0.120-inch space. The bottom 
and angles are not ground, but the tops of all the sections are 
ground when they are assembled in the cast-iron bolster /, 
Fig. 7. Two set-screws J are provided to take care of the end- 
thrust on the die sections. The length of the die is 9 inches, 
but if it is found that this dimension is slightly exceeded, it is 
an easy matter to lap the sections off on the sides to reduce it the 
required amount. 

The cast-iron bolster is held securely to the press bed by 
means of four f-inch hexagon screws. The gib K runs through 
the entire length of the die-bolster and is held against the die 
sections by four set-screws L. On top of the bolster, there are 



SECTIONAL DIE DESIGNS 



257 



two soft-iron plates M and N. 
The plate M is held in position 
by five fillister screws and acts 
as a stop-wall for the work to 
rest against in the die. This 
plate has slots milled along its 
edge which correspond with the 
die section, only they are a 
few thousandths larger than the 
punches; the plate M also acts 
as the stripper for the punch. 
The plate N slides back and 
forth on the bolster under the 
strap P, its movement being con- 
trolled by the cam and lever 6*. 
The hardened wedge R is driven 
into the middle of the plate for 
the cam S to rest against and 
when the cam is swung around to 
bring the flat section into engage- 
ment, the springs Q at each end 
of the die pull the plate N back 
so that sufficient space is made 
to lift the finished work out of 
the die. 

There are two f-inch holes 
provided in the bolster to re- 
ceive the pilots B of the punch- 
holder, Fig. 8. These holes have 
hardened bushings driven into 
them which can be replaced 
when they become worn to an 
objectionable extent. The 
punch sections are held in a 
machinery steel holder A shown 
in Fig. 8. This holder is finished 
all over, great care being taken 



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258 SECTIONAL DIES 

to secure the necessary alignment. The guide pins B are 
hardened, ground, and lapped to exact dimensions and the same 
gage H (Fig. 9) that was used for measuring the die sections is 
also used in determining the accuracy of the punch sections. 
These punch sections are secured to the holder by fillister screws 
E, sl single screw being used between two sections in the manner 
shown in the illustration. The clamp F runs the entire length of 
the holder and is held in position by the fillister screws G. Two 
set-screws H are provided to take up any end-thrust in the 
punch sections. 

It may appear that this punch and die is rather complicated, 
but this design seemed to be the only one that could be main- 
tained in working condition; moreover the working parts are 
relatively simple, and were not as expensive to make as it might 
appear. The forming of the type-bar plates A (Fig. 9) is done 
in two operations. The stock is rolled on a spool and held in 
the proper position to be received by a powerful trimming, 
press. In the first operation, the stock is cut off and formed 
to. the right angle; the downward stroke of a roller at the back 
of the die then curves the other edge of the plate upward to form 
a quarter segment. The second operation is done separately 
in a clamping die and forms the plate to the required shape. 

Making Sectional Die Parts. — The making of sectional dies 
for armature disks and work of a similar kind calls for con- 
siderable ingenuity on the part of the toolmaker in devising 
means for producing these parts accurately and economically. 
It is necessary, if the best results are to be obtained, to secure 
a steel which will not warp or distort during the hardening 
process so that grinding of the parts after hardening may not 
be necessary. Should the die and punch sections warp or 
shrink, it adds greatly to the difficulty of manufacturing the 
parts and greatly increases the cost of the tool. In many cases 
grinding of the die and punch sections is necessary, so that 
special devices and tools have been devised for handling this 
work as expeditiously as possible. In the following, a number 
of the most interesting methods employed by the Columbus Die, 
Tool & Machine Co. will be given. 



MAKING SECTIONAL DIE PARTS 



259 



Grinding the Die Sections. — In order that the die sections 
will fit properly in place after hardening and give the required 
outside and inside diameters, it is necessary to leave a slight 
amount of excess stock on the sides of the sections that fit 
against each other in the die-holder. These sides are then 
ground to the required angle and thickness in a special fixture. 
The toolmaker figures out the required angle of the side sections 
and also the least or greatest thickness. The type of fixture 
used for grinding these die sections for armature disk dies is 




Fig. 10. Grinding Die Sections 

shown in Fig. 10. It consists of an ordinary angle-plate A 
which is fastened to the table of a grinder of the surface type, 
and against which is held another angle-plate B that can be set 
around to the desired angle and carries the work to be ground. 
The work or die section C in this case is held in place by a special 
toe clamp, and when one side of the section is ground it is re- 
versed and the other side is ground. 

The sides of the punch sections are ground in a similar manner 
on the same fixture which, however, is swung around into the 
position shown in Fig. n. The punch section A is held to the 
small angle-plate B as illustrated, and when one side is ground 
the section is reversed on the angle-plate and the other side 
finished. When the fixture has once been set up, however, all the 
punch or die sections are ground on one side first. Then 



260 SECTIONAL DIES 

the setting of the machine is changed and the other side of all 
the sections ground. This enables the toolmaker to turn out the 
work much more quickly than if he were to reset the machine 
for both sides of the piece, thus finishing it complete without 
removing it from the fixture to put another in its place. 

Special Chucks for Holding Die and Punch Sections. — In 
Fig. 12 are shown two special chucks which are used for holding 
punch and die sections while grinding the inside and outside 




Fig. ii. Grinding Punch Sections 

diameters and the top and bottom faces, so that all the im- 
portant machined surfaces can be finished at the same setting. 
The special chuck for holding the punch sections is shown to 
the right of the illustration. This, as can be clearly seen, con- 
sists of a cup-shaped body A around the periphery of which are 
located set-screws B. These set-screws bear against the backs 
of the sections and bind them together, the beveled surfaces of 
the punch sections being wedged together by the action of the 
set-screws, and consequently held rigidly in place for the grind- 
ing operation. The grinding is done in a cylindrical grinding 
machine, the chuck being screwed to the nose of the spindle in 
the ordinary manner. The outside surfaces are ground tapered 
to an angle of 5 degrees to enable them to be held in place in 
the punch-holder by a retaining ring. 



MAKING SECTIONAL DIE PARTS 



261 



The special chuck for holding the die sections for grinding is 
shown to the left of the illustration. Here only four die sections 
C are shown in place, simply to indicate the manner in which 
they are held. The narrow portion of the die section is a drive 




12. Special Chucks for Holding Die and Punch Sections 
while Grinding 




Fig. 13. Assembling a Sectional Armature Disk Punch 

fit in the slots of the die-holder and these sections are tapped 
lightly into place until the beveled surfaces contact. The 
chuck D is also held in a cylindrical grinder, being screwed to 
the nose of the spindle as previously mentioned in connection 



262 



SECTIONAL DIES 



with the chuck for the punches. This chuck enables the inside 
and outside diameters of the die sections to be ground and also 
the top face. The lower face is ground by reversing the position 



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Fig. 14. Milling Segments for Pole-piece Punch 

of these sections in the chuck, and then holding them in the 
manner in which they are held in the illustration. 

Assembling an Armature Disk Punch. — After the beveled 
sides of the punch sections have been ground, as previously de- 
scribed, it is then necessary to test these sections to see whether 
the correct inside and outside diameters have been secured, and 



MAKING SECTIONAL DIE PARTS 



263 



also if the small projections on the inner surfaces of the punch 
sections are properly located axially. This, of course, proves 
whether the correct amount of stock has been ground from the 
sides of the punch sections. The fixture used for this purpose 
is shown in Fig. 13 and consists of a block A, circular in shape, 
in which a stud B is located. This stud acts as a means for 
holding the gage C, which, as can be seen, is cut to fit over the 
projections on the punch sections and is also fitted over the 
stud, being centrally located in this manner. In this particular 




Fig. 15. Boring Sub-press Die Guide-pin Holes 

case, a limit of only 0.0005 inch is allowed from the center of the 
plug to the inside face of the punch section. Also the blank 
must be reversible on the punch. When it is realized that these 
dimensions are governed entirely by the amount of metal re- 
moved from the sides of the sections, it will be seen that the 
grinding operation is one that must be very carefully handled 
and that requires considerable ingenuity on the part of the tool- 
maker if the parts are to assemble accurately. 

Milling Segments for Pole-piece Sectional Punches. — Fig. 
14 shows how segments for pole-piece sectional punches are 
milled both on their circular and angular faces. A Knight 
milling and drilling machine is used for this purpose, being 
equipped with a circular milling attachment A. The section B 



264 SECTIONAL DIES 

of the pole-piece punch to be machined is clamped to the top 
face of the circular milling attachment by clamps as illustrated, 
and the machining is accomplished by an end-mill C held in the 
spindle of the machine. The circular attachment is operated 
by a bar D which can be located in holes provided around the 
periphery of the faceplate. For milling the beveled faces, the 
circular attachment is clamped to prevent it from rotating and 
the feed-screw for the table is operated. 

Boring Sub-Press Die Guide-pin Holes. — After all the vari- 
ous members of the sectional punch and die have been com- 
pleted, they are assembled in the punch- and die-holders and 
then the next operation is to bore the holes for the aligning 
pins, when the dies are of the sub-press construction, which is 
the usual type of construction adopted for complicated sectional 
punches and dies. The manner in which these guide-pin holes 
are machined is shown in Fig. 15. The punch- and die-holder 
are located in the proper relation to each other and are fastened 
together by through bolts as illustrated. Then these holders 
for the sectional members are located on the table of a milling 
machine and the holes are first drilled and then bored by a 
boring tool held in the spindle of the machine. The two lower 
holes are bored and counterbored first, the center distances, of 
course, being located by the micrometer dial on the feed-screw. 
Then the table is lowered and the top or two remaining holes 
are bored and counterbored in a similar manner. This method 
of boring the guide-pin holes enables them to be produced 
quickly and accurately with very little difficulty. 



CHAPTER VII 

AUTOMATIC FEEDING AND EJECTING MECHANISMS 
FOR PRESSES 

Power presses for producing articles made from sheet metal 
are equipped with many devices for automatically feeding the 
strips of flat stock or blanks to the dies. In addition to the 
economy of a more rapid production, the application of auto- 
matic feeds to power presses assists in protecting the hands of 
the operator, because the automatic feeding mechanism makes 
it unnecessary for him to put his hands near the dies. Various 
forms of feeding mechanisms are applied to presses of every 
type, the kind of feed used depending upon the material to be 
handled. The types of automatic feeding mechanisms most 
generally employed are the single and double roll, grip, gravity, 
push, dial, and reciprocating feeds. There are numerous ways 
of applying these types of feeds to power presses in order to 
adapt them to the specific requirements. Frequently feeds of 
two types are combined to facilitate production. Some feeds 
are entirely automatic, the operator having only to keep the 
machines constantly supplied with the metal from which the 
punchings are made; however, on dial and other feeds which 
only automatically carry the work forward, under and away 
from the dies — especially on riveting, assembling, clinching, and 
forming operations on pieces previously blanked or cut out in 
another press — an operator is required to feed each separate 
piece into the feeding mechanism which then carries the work 
to the dies. 

Single-roll Feed. — In Fig. i is illustrated a single-roll feed 
fitted, in this case, to a straight-sided press. This type of feed 
is used for feeding strip stock, but the particular feeding device 
illustrated is not built in the regular manner, as the work for 
which it is used requires a very accurate feed — more accurate 

265 



>66 



FEEDING MECHANISMS 



than could be obtained with the regular size of standard single- 
pawl feed. The difference in construction from the regular toed 
is in the ratchet .1. which is operated by three pawls held to a 
segment disk B. This feature reduces the inaccuracy in feed- 
ing to a minimum without the use oi a ratchet three times the 
circumference of the single pawl ratchet, which would be neces 
sarv to obtain the same result with the ordinary type of teed. 

This ratchet iced can be adjusted for a wide range of length 
of feeds, the adjustment being made by means oi an adjusting- 




Fig, i. Straight-sided Press Equipped with Single-roll Ratchet Feed 

screw in the block C, held in the eccentric arm on the end ot the 
crankshaft. Power is transmitted from the eccentric arm D to 
the roll shafts through the ratchet .1 and pawls, the connecting- 
rod E being tit ted with universal joints. The roll shafts are 
connected by gears, as shown, and to avoid over-feeding, due to 
the momentum of the feeding parts, the lower roller shaft is 
fitted with a brake. The feeding device in this case is situated 
at the rear of the press, but it can also be arranged either in 
front or to the right- or left-hand sides, as desired. 



SINCiLE-ROLL FEED 



267 



Another type of single-roll feed, fitted to an inclinable press, 
is shown in Fig. 2. This feed differs from the one shown in 
Fig. 1 in the method of driving, the rack type of drive being 
used instead of the ratchet type. The rack type of drive is 
largely used for long feeding, as it gives a wider range of feed, 
with the same sized rolls, than can be obtained with the ratchet 
feed. It is not advisable to feed over 90 degrees, or one-quarter 
turn of the rolls, with a ratchet feed, but with the rack feed 




Fig. 2. Inclinable Press having a Rack-operated Roll Feed 

several revolutions of the feed rolls can be made for one stroke 
of the press. This permits the use of small feed rolls, making 
a smaller and more compact attachment. 

Automatic Release for Feed Rolls. — The feed rolls shown in 
Figs. 1 and 2 are provided with an automatic release, this being 
more clearly shown in Fig. 2. This automatic release of the 
rolls is necessary when pilots are used in the punches. The 
operation of the automatic roll release is as follows: 



268 



FEEDING MECHANISMS 



Referring to Fig. 2, the feed rolls A and B are held in con- 
tact by means of springs C. The lower bearing in which the 
roll A is held, is stationary, while the upper bearing carrying 
roll B is movable. The releasing device consists mainly of a 
bar D, attached to the ram of the press, in one end of which 
is a set-screw E. The point of this set-screw bears on an arm 




Press Equipped with Double-roll Feed 



F which is cast integral with the top roll bracket. As the ram 
of the press descends, the screw E comes in contact with the 
arm F, releasing the stock when the pilots in the punches enter 
the die. The stock is then free so that it can readily be shifted 
by the pilots if necessary. It will be noticed that the roll re- 
lease arm F is provided with a handle so that the upper roll can 
be released by hand when starting a new strip. 



DOUBLE-ROLL FEED 



269 



Double-roll Feeding Attachment. — Fig. 3 shows what is 
termed a double-roll feed attached to an open-back inclinable 
power press. The press, when in use, is set on an incline, thus 
permitting the cut and formed work to automatically fall away 
from the dies by gravity. This style of feed is applicable to al- 
most any type of press but, like most other feed mechanisms, it 
is adapted only to work produced from a flat sheet or coil, either 
with plain blanking or cutting dies or with combination cutting 




Fig. 4. Double-roll Feeding Mechanism applied to Straight-sided Press 

and forming dies. Roll feeds consist of rolls of varying diameter 
and length, with a variable "feed-stroke," and while they insure 
accurate feeding and a saving in material, their actual value to 
each individual manufacturer depends primarily upon the size 
and shape of the article made, the construction of the dies, and 
whether single or gang dies are used. 

The feeding device attached to the press in Fig. 3 is adjust- 
able by sixteenths for feeding up to if inch at each stroke of 
the press. The journals or boxes for supporting the rolls are 



270 FEEDING MECHANISMS 

adjustable to accommodate varying gages of metal. Pivoted 
releasing-levers or arms, bearing upward against powerful 
springs in each of the journals supporting the upper rolls, ex- 
tend inwardly and under adjustable set-screws attached to the 
slide or ram of the press. Depending upon the manner in which 
they are attached, these roll feeding devices can be arranged 
to feed the stock from front to back or vice versa, or from right 
to left or vice versa. The stock is fed forward on the up-stroke 
or return of the shaft and slide, and as the slide descends, the 
set-screws mentioned, bearing down on the pivoted releasing- 
arms, lift up the upper rolls momentarily, releasing the pressure 
upon the strip of metal, so that, in the event of any unevenness 
in the thickness of the metal or any variation in the feeding, a 
pilot or guide pin on the dies may locate the strip before the 
dies actually perform their work. 

Fig. 4 shows a special double-roll feeding mechanism operating 
on a straight-sided press equipped with gang dies for performing 
various operations on strip steel for expanded metal lath. The 
stock is fed into the machine in flat strips previously cut to the 
proper width. The first or forward set of rolls has a series of 
milled V-grooves for ribbing the flat ribs longitudinally as they 
are fed into the machine. Passing from this first set of rolls 
into the dies, the strip is gradually slitted and expanded, and 
then automatically discharged by the rear set of rolls ; the latter 
have, besides the V-grooves, a series of slots cut in them to 
match the shape of the stock that is slitted. This feeding device 
is adjustable for feeding up to 2 inches at each stroke of the 
press, the machine operating at 250 R.P.M. 

Rack-and-pinion Double-roll Feed. — In Fig. 5 is shown a 
small open-back inclinable press fitted with another special 
double-roll feeding mechanism. In this case, instead of having 
the eccentric or feeding arm connecting the cam on the shaft 
directly with the rolls, the drive is imparted from an eccentric 
on the shaft to a vertical-traveling rack, which, through its 
pinion and a series of bevel gears and an endless chain, acts as 
the drive for the rolls. This construction is what is termed a 
"rack-and-pinion" feed, and is resorted to in many cases where 



DOUBLE-ROLL FEED 



271 



the work is of such a nature that it is desired to have the front 
of the press as open and free from arms as possible, to insure 
complete accessibility to the dies and work. This is the prime 
reason for the use of this construction in this instance. The 
purpose of the press is the cutting out of corn plasters. The 




Machinery 



Fig. 5. Press Equipped with Rack-and-pinion Double-roll Feed 

medicated cloth for the plasters, in strips about 4 inches wide 
and 48 inches long, is fed into the machine on a hard maple 
board of a slightly greater length and width, the board being 
fed forward about if inch at each stroke of the press. The 
work is performed by a group of hollow punches of the same 



272 



FEEDING MECHANISMS 



construction as those regularly employed for cutting cloth, paper 
and other fibrous materials. The first set of three punches cuts 
out only the center or "corn" opening, while, at the following 
stroke of the press, as the stock is fed forward, the second set 
of three punches cuts out the completed cloth ring for the 
plaster. The punches for cutting the center opening are so con- 
structed that the cloth is pushed up into them, and gradually au- 
tomatically ejected through an opening in the back of the slide or 




Fig. 6. Toggle Drawing Press having Push Feed and Magazine 

ram to which the punches are attached. After the second oper- 
ation the cut disks or rings are removed or stripped from the 
punches (or, more literally speaking, cutting dies) ; they are left on 
the maple board and taken back to the work-bench where the 
simpler operations are performed by hand to finish the plaster. 
In the meantime another board with its strip has been fed into 
the machine. The machine operates at 100 R.P.M., producing 
300 rings per minute. 



SLIDE AND DIAL FEEDS 273 

Push Feed. — The toggle drawing press shown in Fig. 6 is 
provided with a push feed, the operation of which is simple. 
The flat blanks (which have previously been cut out) are placed 
in the magazine A , from which they are removed one at a time 
to the dies, the feeding being accomplished by a traversing slide 
receiving its motion through rods B and C, and levers D and E. 

Slide Feeds. — The feed mechanism attached to the small 
press in Fig. 7 is designed for use in connection with parts re- 
quiring forming operations, which, owing to the irregular shape 
of the pieces, make hand feeding necessary. Even experienced 
operators are at times careless in feeding or removing the work 
and also in starting the press. The slide feed shown eliminates 
accidents from such causes, as the only time that the operator's 
hands are near the dies is after the operation has been com- 
pleted, the press stopped, and the dies returned to the front of 
the press for the removal of the finished piece and the insertion 
of another. After placing the piece in the dies and "tripping" 
or starting the press, the dies are automatically carried back to 
their proper position under the forming punch by means of the 
toggle-arms connected to the cam and eccentric collar on the 
end of the shaft. This cam provides not only a positive, quick 
feed, but also a quick return of the dies to the front of the press 
after the work is finished. This style of feed is extensively em- 
ployed in connection with the manufacture of small odd-shaped 
automobile radiator tubing, bottle caps, jewelry, and gas fix- 
tures. 

Ratchet Dial Feeds. — Fig. 8 illustrates what is designated as a 
dial or rotating feed, because of the fact that the work is auto- 
matically carried forward to and away from the dies by a con- 
tinually revolving dial or feeding-table. This table is operated 
by a pawl and ratchet connected with an eccentric attached to 
the shaft of the press. The feeding dials are provided with 
holes varying in number according to the size and shape of the 
work and the size of the bed of the press to which the feed is 
fitted. Into each of these holes is fitted a tool-steel bushing or 
chuck with a milled opening to match the shape of the piece to 
be operated upon. These bushings are removable, a different 



274 



FEEDING MECHANISMS 



set of bushings being required for each shape or size of piece. 
To prevent the pieces from dropping through these openings in 
the bushings until the dial brings them to the dies, a stationary- 
cast-iron plate is bolted onto the bolster or bed-plate of the 
press, directly beneath the revolving dial. This plate has open- 
ings to correspond only to the dies used. In some cases the cut 
pieces, ready to be formed, are automatically fed into the dial 
or rotating plate by a hopper or tube rigidly secured to the press 





Fig. 7. Press Equipped with Slide 
Feed Mechanism 




Ratchet Dial or Rotating 
Feed Mechanism 



bed. This, however, is feasible only on circular, square, or 
other regular shaped blanks. Irregular shaped blanks must in 
almost all cases be fed into the dial by hand, and as speed is 
the principal reason for the employment of this style of feed, it 
should be so arranged as to leave the front or feeding end of 
the press and feeding-table as accessible as possible for the oper- 
ation. This is the distinctive feature of the dial-feeding mechan- 
ism shown in Fig. 8. 

Dial-fed presses are widely used by manufacturers of curtain 
brackets, cartridges, locks, hardware stampings, and, in general, 



DIAL FEEDS 



275 



for articles requiring several forming operations, the dial-feed- 
ing mechanism permitting the use of dies for performing from 
one to four successive operations on certain classes of stampings 
in one press. One western telephone manufacturer uses one 
press fitted with a double-roll feed and ten other presses fitted 
with dial feeds for performing twenty-nine operations on a 
single stamping of light gage steel and of a very irregular shape. 
The dial-fed press shown in Fig. 8 is also fitted with an auto- 
matic bottom " lift-out" (not shown) for ejecting the finished 
stampings from the dies, and with an automatic safety device 




Fig. 9. Front View of a Dial Feed Operating Mechanism 

attached to the trip-lever for the clutch, which automatically 
stops the press if the dial is not properly fed forward. 

Presses equipped with the ratchet dial feed are generally pro- 
vided with a safety device. This device is so connected with 
the clutch used in stopping and starting the machine, as to 
stop the ram on its downward stroke before it can do any harm, 
if it should so happen that the dial is prevented from assuming 
its correct relative position. A safety device of this kind is ap- 
plied to the dial feed described in the following. 

Another design of ratchet dial-feeding mechanism is illustrated 
in Figs. 9 and 10 which show front and rear views of the mechan- 
ism which controls the operation of the dial. Referring to these 
illustrations, it will be seen that the pawl is mounted on an arm 
A which causes it to move in a circle concentric with the dial. 



276 



FEEDING MECHANISMS 



The link B is connected to the end of the pawl which is shaped 
like a bellcrank, and there is a stop on the arm A which limits 
the motion of the pawl. The link B is operated by the arm C, 
which is pivoted at a point behind the right-hand upright of 
the press; this arm is, in turn, operated by the roll arm D, the 
two members being connected by an adjustable sliding block 
which may be regulated for the use of any number of notches in 
the dial from 12 to 24. The pawl, together with the complete 
dial driving mechanism, is returned by a spring which is located 
in such a way that it acts on both the levers C and D, eliminat- 
ing lost motion from the mechanism. 




Fig. 10. Rear View of Dial Feed Operating Mechanism 

The timing of the dial operating cam, which, as shown, is 
mounted on a side shaft and driven from the left-hand end of 
the crankshaft by bevel gears, is such that the dial starts to 
move forward when the ram is half way up and the indexing of 
the dial is completed at or before the time when the ram reaches 
the highest point of its stroke. The cam holds the pawl and 
dial in this position until the ram has practically reached the 
lowest point of its stroke, and by this time the tools have en- 
tered the dial so that, before the pawl releases it, all possibility 
of its shifting out of place has been eliminated. When the 
pawl starts to move back, the first part of the motion consists 
of lifting the pawl out of the dial notch, this motion being 
limited by the stop in the lever A . The lever A is then carried 



DIAL FEEDS 277 

back until the pawl has been brought into position to enter the 
next notch in the dial. During this time, the ram has moved up 
and if, through the breaking of any part or from some other 
unusual condition, the dial is not indexed to the right place, 
the locking lever E, which is mounted on the lever C, will not 
enter the slot in the dial, and as a result, the opposite end of 
the lever E will engage the stop on lever F, thus holding this 
lever up and making it impossible to engage the clutch for the 
next stroke of the press. The arrangement of this mechanism 
is clearly shown in Fig. 10. 

In running a dial press, it sometimes happens that the knock- 
out will fail to bring the work out of the die or that the bottom 
of a shell will be torn out in drawing it through the die, thus 
leaving a shell between the die and the dial. To avoid a serious 
accident in the event of an occurrence of this kind, the link B 
is so designed that it will be bent or broken before any other 
part of the press gives way, and as this link is simply a piece of 
cold-rolled stock, an accident of this kind is not serious. The 
clutch furnished on these machines is of the standard key type 
and the knockout is operated from cams carried on an under 
motion shaft, the cams acting directly on the end of a straight 
knockout rod. 

Friction Dial Feed. — This type of feed mechanism has a 
plain disk which revolves continuously, instead of having an 
intermittent motion like the ratchet dial feed. The disk is 
used in combination with stationary guides and gages above it, 
so that the work placed on the revolving disk is accurately 
carried around under the punch. In order to insure reliable 
action, a finger or gripping mechanism is usually provided 
which locates and holds the work in the right position for the 
descending punch. The friction dial feed is adapted for re- 
drawing short shells or parts which are not liable to topple over. 

Friction Dial and Push Feeds. — In Fig. 1 1 is shown an in- 
clinable power press to which is fitted an automatic friction dial 
and also a push feed. This press is used for reducing and stamp- 
ing shells which have been, previously cut out and drawn in an- 
other press. In operation, the shells are placed on the table A 



278 



FEEDING MECHANISMS 



from which they are removed to the revolving dial B, the top 
of which is flush with the table. The dial B carries the blanks 
to an automatic stop from which they are released one at a 
time by the cam and spring-actuated feed-arm C, carrying them 
to the dies. The arm C, which is pivoted to the bracket D, is 
actuated by a cam E on the vertical shaft F. This shaft de- 
rives its power through the bevel gears shown, one of which is 
attached to the end of the crankshaft. From the vertical shaft 




Fig. ii. Press Equipped with Combination Friction-dial and Push Feed 

F, power is also obtained to drive the revolving dial B through 
pulleys G and H, by a round belt running over suitable idlers. 
Another feature of this press which might well be mentioned, 
but which in a measure could not be considered a feed, is the 
method used in removing the finished blanks. This is ac- 
complished by means of a continuous operating endless belt 
fitted between the sides of the press and driven by a belt run- 
ning over the hub of the flywheel. After the first blank has 
been fed to the dies and operated upon, the blank following it 
is carried to the die by means of the feed-arm which pushes the 



DIAL FEEDS 



279 



first blank off the die onto the conveyor, the latter depositing 
the blank in a suitable receptacle. 

Friction Dial and Reciprocating Feed. — A combination auto- 
matic friction dial and reciprocating feed fitted to an inclined 
press is shown in Fig. 12. Three operations are performed si- 
multaneously by this press. Presses fitted with this combination 
of feeds are particularly adapted for the production of pieces 
on which there is a series of operations. The shell to be oper- 




Fig. 12. Press having a Combination Friction-dial and Reciprocating Feed 

ated upon in this press is previously cut out and drawn in 
another press fitted with a feed similar to that illustrated in 
Fig. 11. After the shells have been blanked and drawn they 
are placed on the continuously revolving dial A which carries 
them up to an automatic stop from which they are released one 
at a time. Here they are gripped by the traveling jaws of the 
reciprocating feed which automatically carry them to each of 
the three dies B, C, and D in consecutive order, finally discharg- 
ing the finished product at the other end of the press. 

The revolving dial A is driven by a round belt from a grooved 



28o 



FEEDING MECHANISMS 



pulley on the flywheel shaft. This belt is changed from a 
vertical to a horizontal position to drive the pulley attached to 
the dial shaft by means of idlers. The reciprocating motion of 
the traveling jaws E is derived from lever F, which is actuated 
by the "race cam" G on the end of the crankshaft. The auto- 
matic opening and closing of the jaws E is accomplished by 
motion transmitted from cam H through bellcrank /, link /, 
rod K, link L, and levers M and A 7 . By means of the handle O, 




Fig. 13. Chute and Hopper Feed Arrangement 

the traveling jaws E may be independently opened at any 
position. After the first three revolutions of the crankshaft, 
the press performs three operations at every stroke. 

Chute and Hopper Feed. — The development of the auto- 
matic manufacture of tin cans and articles of pieced tinware has 
brought out many automatic feeds and other press attachments. 
An interesting: automatic feed for this class of work is shown 



CHUTE AND HOPPER FEED 



281 



in Fig. 13. A horning and riveting press is here shown fitted 
up for automatically assembling and clinching the ears on lard 
pails, for holding the wire which forms the pail-handle. Instead 
of the operator using one hand to hold the pail and the other to 
place the ear on the clinching die, he merely places the pail on 
the die, which is attached to the horn or mandrel shown, trips 
the press, and the punch, descending on the pail and ear (the 
latter being previously fed to and located on the lower die), 
securely clinches the two tightly together. The revolving hopper 
A is filled with ears, and as it rotates the ears fall by gravity 
through the various openings in the side or wall of the hopper 




Fig. 14. 



Simple Feed Chute Attachment for Turning Shells which Enter 
Open-end Foremost 



and into the chute B. The chute does not convey the ears 
directly to the die, but to a point about ij inch to the rear of 
the die. The press and dies are fitted with a sliding arm or feed 
finger located at the rear of the dies and connected with the 
slide or ram of the press proper by means of a pair of links. As 
the slide recedes from the work on the up-stroke, these links 
force the sliding feed-arm forward a fixed distance, and as the 
arm moves past the open end of the chute, it carries one ear 
forward and onto the dies. The arm remains in this position 
until the press is tripped. When the press is tripped and the 
slide descends, the motion of the links returns the feed-arm to 



282 FEEDING MECHANISMS 

its normal position at the rear of the dies, permitting another 
ear to slide down in front of it. This arrangement gives the 
operator the entire use of both hands. 

Feed Chute for Drawing Press. — An interesting form of feed 
chute that is used to prevent the breakage of drawing punches 
in shown in Fig. 14. The press on which this device is used is 
employed in performing a drawing operation on the cups shown 
in the illustration. These cups enter the chute A from a hopper 
and pass down quite rapidly; when the bottom of the cup strikes 
the pin B the cup rebounds and drops into the feed-pipe C, 
which leads to the feed ringers of the press. It is necessary to 
have the cups feed into the press with the closed end down, but 
sometimes a cup enters the chute A in an inverted position, as 
shown by the right-hand view. If the cup reached the die in 
this position, it would result in breaking the drawing punch. 
A simple and ingenious method of turning a cup is indicated by 
the illustration to the right. If the cup enters the chute A 
with the open end foremost, it slides down until it catches on 
the pin B, and, instead of rebounding, swings on the pin B and 
drops into the feed-pipe C with the closed end down in the 
manner illustrated. This feed chute is carried by a bracket 
which is attached to a stationary part of the press. 

Knockout for a Punch-Press. — The mechanically operated 
knockout shown applied to a punch-press in Fig. 15 operates 
more satisfactorily than a rubber bumper — especially for brass 
forging dies and small redrawing dies — and is less expensive. 

The view to the left shows the attachment in place on a 
punch-press. Referring to this illustration, A is a crank disk 
which is bored out to fit over the projecting end of the crank- 
shaft to which it is fastened by means of two bolts shown at L. 
(See detail view at the right.) Adjustment of the length of the 
stroke is provided by means of a T-slot in which the crank-pin 
K is secured, and the knockout can be timed to suit the require- 
ments of the work on which the press is engaged by loosening 
bolts L and turning disk A to the right or left with relation to 
the crankshaft. The hubs B at each end of the connecting-rod 
C are alike, except that one hub is threaded right-hand and the 



284 FEEDING MECHANISMS 

other left. The connecting-rod C has a flat on it which can be 
engaged by a wrench, and by turning the rod a very fine adjust- 
ment of the knockout is secured. Further adjustment may be 
made by using different sizes of washers / and knockout pins /. 

The collars E support bearings in which the shaft F turns 
and these collars have four short legs cast on them, it being pos- 
sible to file the legs to compensate for irregularities in the frame 
of the punch-press on which the attachment is to be applied. 
The collars are fastened to the bed of the press by four half- 
inch cap-screws. The crank D is keyed to the shaft F and the 
same method is used in securing the cam G in place. The 
bracket H has four short legs cast on it so that it may be fitted 
to the rough bed casting and fastened by two cap-screws. The 
hole in this bracket is bored large enough so that the knockout 
pin / is a sliding fit in it. 

The method of adjusting this attachment is as follows: When 
the ram of the press is in the upper position, the crank A is set 
with the slot vertical. The hub B is next fastened to the lower 
end of the slot by means of the stud shown at K. On the down- 
ward stroke of the ram, the crank disk A makes one-half revo- 
lution, thus raising the connecting-rod C and crank D. The 
cam G turns and lowers the knockout pin / and collar J. Then 
when the ram begins its up-stroke, the crankshaft completes 
the revolution, pushing down the connecting-rod C and the 
crank D, and raising the pin / and collar / through the action 
of the cam G. In this way, the work is ejected from the die. 
In some cases corrugations are milled on the inside of the crank 
disk and the brake hub, to prevent the collar from slipping. 

Ejecting Press Work with Air Blast. — An arrangement for 
blowing work from a forming die in a punch-press, -by means 
of compressed air, is shown in Fig. 16. It is simple and durable, 
and is used on about forty presses in a large plant, with satis- 
factory results. The illustration shows a plain forming die in 
position under the plunger of a press, while at the left of the 
plunger is the air valve A with its attachments. This valve is 
a Lunkenheimer whistle valve. It is held by the pipes which 
are screwed into each end, these pipes being held by the brackets 



AIR BLAST EJECTOR 



285 



which are screwed to the frame of the press. Below the valve 
there is a union and some other connections, and a bent tube 
which may be turned so as to apply the jet of air most ad- 
vantageously. In some cases two unions are used to facilitate 
the adjustments. The lever of the whistle valve has been re- 
moved and in its place the trigger is mounted. This trigger is so 




O a O 



^~\ 



Machinery 



Fig. 16. Pneumatic Press Attachment for Automatically Removing 

Work 

designed that it remains vertical when not in action; it is seen 
in position against the plunger of the valve. The trigger is oper- 
ated by the pawl C which is mounted on the bracket D. The 
bracket is made of angle iron and is provided with two long slots 
for adjustment when the dies vary in thickness. 

As the plunger descends, the end of the pawl C rises, as shown 
by the dotted outline, and passes below the head of the trigger 



286 



FEEDING MECHANISMS 



B. On the upward stroke the end of the pawl engages the cam 
on the end of the trigger and thus operates the valve. In this 
way a jet under full pressure is suddenly directed against the 
work, blowing it out of the operator's way before the plunger 
reaches its highest position. 

Another arrangement for blowing away finished stock from 
a punch-press is illustrated in Fig. 17. As there was no com- 
pressed air of sufficient pressure available, an independent pump 




r 



Machinery 



Fig. 17. 



Press Equipped with Air Pump for Ejecting Work 
Section of Pump 



Enlarged 



was attached to the press, as shown. The piston-rod of this 
pump is connected to the cross-head of the press, and, con- 
sequently, the pump has the same stroke as the throw of the 
crankshaft. The air is compressed on the up-stroke, and it is 
delivered against the work by means of a |-inch pipe which is 
fitted on the end with a nozzle. The pump cylinder is made of 
a piece of 3-inch brass tubing which is screwed into a baseplate, 
as shown in the enlarged sectional view. This tubing is fitted 
with a head containing a stuffing box, and a |-inch pipe outlet. 
The piston is a regular 3 -inch hydraulic cup, and a piece of 
leather belting is used as packing. A piece of leather fastened 
by one screw to the inside of the piston, acts as an inlet valve. 



CHAPTER VIII 

TOOLS FOR PERFORATING CYLINDRICAL AND CONICAL 

WORK 

The punches and dies used for perforating the sides of cylin- 
drical work are similar to blanking punches and dies, except for 
the modifications necessary, owing to the fact that the metal 
which passes over the face of the perforating die is circular in 
form instead of being flat. Circular perforating tools are used 
in connection with this class of work because the nature of the 
work is such that, on account of both commercial and mechan- 
ical considerations, it cannot be carried out in any other way. 

In Fig. i is shown a set of perforating tools together with a 
perforating attachment set up in a press ready for perforating a 
shell similar to the one shown in Fig. 3. The shell is first slipped 
over the die-holder (Fig. 4) in such a manner as to allow the 
elongated slot A in the bottom of the shell to engage with the 
projecting tongue of the driving arbor. The press is then tripped 
and the punches, at the first stroke of the press, cut out two of 
the irregular shaped perforations B in the shell. On the up- 
ward stroke of the press, a pawl A, Fig. 1, by the aid of a ratchet 
B, ratchet shaft C, and the bevel gears, revolves the driving 
arbor, which rotates the shell a part of a turn. As the slot in 
the bottom of the shell is engaged with the tongue of the driv- 
ing arbor, the shell is indexed with the arbor before the punch 
descends again. These operations are continued until the press, 
in this case, has made fourteen continuous strokes, when it is 
automatically stopped and the perforated shell removed. The 
stopping of the press is effected by cam D, which automatically 
releases the driving clutch when the required number of strokes 
has been made. The construction of the tools and the manner 
in which they are made will be treated later. 

In Fig. 5 is shown another set of perforating tools for per- 

287 



PERFORATING DIES 



forating the gallery fence of a lamp burner shown in Fig. 6. 
The gallery fence of a lamp or gas burner holds the lamp chimney 
or globe in place by the spring pressure exerted by the perforated 
part. The metal must be hard in order to impart the required 
spring pressure and is, therefore, on the better grade of burners, 
burnished before perforating, which not only hardens and 
toughens the metal, but also produces a brilliant finish. On 




Fig. i. Press with Attachment for 
Perforating Shell shown in 
Fig. 3 



Fig. 2. Perforating Attachment with 
Special Device for Holding Shell 
in Place 



the cheaper grade of burners, the shells from which the gallery 
fences are made are passed through an extra redrawing oper- 
ation, the shells not being annealed, but left hard. The differ- 
ence in the diameter of the shell before and after redrawing is 
about 3V inch, while the difference in the thickness of the metal 
is about 0.0005 inch. This treatment of the metal not only im- 
parts the required springiness, but also makes the perforating 
operations easier, because hard metal is more readily perforated 
than soft. 



PERFORATING CYLINDRICAL SHELLS 



289 



The tools used for perforating the gallery fence shown in 
Fig. 6 are somewhat different in construction from those shown 
in Fig. 1. The ratchet C, Fig. 5, is keyed to the driving arbor, 
and when the tools are set up in the press they are set with the 
face of the die-holder turned towards the right, instead of facing 
the operator. The perforating operation, however, is similar 
to the one already described. The effect of the successive 
strokes of the press is indicated in Fig. 6. At the first stroke of 
the press, the four shaded areas at F are punched out. At G 
can be seen the appearance of the shell after the second stroke. 



■t!t 




Fig. 3. Example of Shell 
to be Perforated 



Fig. 4. Section of Die-bed, Holder and Die 
for Perforating Shell shown in Fig. 3 



In order that no burr or fin may be left on the top points of the 
scallops, the die is made so that the punch will cut a trifle past 
the center of the point as shown at H. The shell is rotated 
towards the left by the driving arbor, and a simple holding de- 
vice, not shown in the illustration, is used for holding the shell 
in place on the arbor. 

An attachment for holding work in place while it is being per- 
forated is shown in Fig. 2. This attachment is used in con- 
nection with the tools for perforating the sides of large narrow 
rings. The tool equipment consists of a perforating punch A, 
and a large die-holder B for holding the dovetailed perforating 
die C. The die-holder is held in die-bed D. The perforating 
attachment, which rotates the shell, is placed directly back of 
the die-bed and is operated by the adjustable connection E, 



290 



PERFORATING DIES 



iiiiy 




^2d4®§ 



fastened to the gate of the press. 
After the ring is slipped over the 
die-holder, handle F is given part 
of a turn to the right which, by 
means of the spiral grooved arbor 
G, causes the circular disk H to 

come in contact with the ring, 
m thus holding it in place. This 
a circular disk rotates with the ring 
e and is attached to arbor G by a 
J2 pin in the hub of the disk which 
a engages with a circular groove in 
en the arbor. 

.« Construction of Perforating 
§ Tools. — In Fig. 7 the perforating 
|> die for the shell in Fig. 3 is shown 
g held in a dovetail channel in the 
g die-holder. The die-holder is pref- 
^ erably made of a cheap grade of 
"§ tool steel, and is held in the die- 
n bed as shown in Fig. 4. The 

1 dovetail method for holding the 

. dies is probably the best, and is 

,2 the one most commonlv used. 
1 

g The sides of the dies are beveled 
•g at an angle of from 5 to 10 de- 
§ grees. For work such as shown in 
« Fig. 3, the die is tapered length- 
wise on one side with a taper of 
. about 1 degree, and is driven into 
£ the die-holder from the back and 
left flush with the shoulder of the 
holder, so that, when in position, 
the die-bed prevents it from shift- 
ing back. When it is possible to 
do so, a pin or a fillister-head 
screw may be used to prevent the 



PERFORATING CYLINDRICAL SHELLS 



>9I 



die from shifting endwise. The shape of the shell and the design 
to be perforated sometimes govern the taper of the sides of the 
die. This, for example, is the case where shells such as shown 
in Figs. 9 and n are perforated, when a greater angle than i 
degree must be used on account of the irregular shape of the 
die-holder and dies. 

The longitudinal cross-section of the die-bed, die-holder, and 
driving arbor used for the shell in Fig. 3 is shown in Fig. 4. 
Section A shows how the arbor is milled at the neck A in order 
to allow the scrap punchings to drop through. A section of the 



Ax ,C ,D 






~7 






J 



Fig. 6. Example of Shell Perforating 

tongue of the arbor which engages the slot in the end of the 
shell, by means of which it is rotated, is shown at B. This 
tongue is tapered as shown, to facilitate the putting on and 
taking off of the work. A scrap escape hole C is drilled in the 
die-holder at an angle as shown, so as to prevent the scrap 
punchings from coming in contact with the shell while it is 
rotated around the die. An escape hole drilled in this manner 
can be used only on short shells and when the scrap punchings 
are small, or, if they are large, when they are few in number. 
Hole D in the die-bed permits the scrap punchings to readily fall 
out of the way. 



292 



PERFORATING DIES 



The construction of the tools shown in Fig. 5 is somewhat 
different. Two small pins E, which are used in the face of the 
driving arbor, act as driving pins for rotating the shell. These 
enter into pierced holes in the bottom of the shell as shown at 
B, Fig. 6. The pawl which operates the indexing ratchet is 




Fig. 7. Die in Position in Die-holder 




Fig. 8. Die, Die-bed and Holder for a Tapered Shell 



fastened to part B in Fig. 5, which is made to fit the shoulder of 
the ratchet and works back and forth in order to provide for 
the required indexing. The back-and-forth motion is imparted 
to B by fastening a handle F to an adjustable connecting-rod 
which, in turn, is fastened to the crankshaft of the press. Part 
D is a brass friction whicff takes up the backlash of the driving 



PERFORATING CYLINDRICAL SHELLS 



2 93 



arbor. This friction is fastened to the die-bed by a screw at G. 
The hole in the center of the friction fits the shoulder on one 
end of the ratchet. The brake or friction effect is applied by 
screw H. Part A acts as a steadyrest for the driving arbor, and 
is fastened to the die-bed by screws J and A'. 

The cam fastened to the end of the driving arbor causes the 
press to stop automatically by coming in contact with a lever 
connected to the driving clutch. The driving arbor is relieved 
at L to prevent the congestion of the scrap punchings. The hole 
for the driving arbor in the die-holder is also recessed at this 



FRICTION 




Machinery 



Fig. 9. Die and Holder for Perforating Shell shown to the Right 

place in order to give the scrap punchings, which, in this case, 
are rather large, ample room to pass the arbor. When the de- 
vice is in operation, a shutter M closes up the bottom of the 
scrap escape hole in the die-holder. When the shell is slipped 
over the latter, the shutter is forced up and thus acts as a trap, 
preventing the punchings from dropping through into the inside 
of the shell. If the punchings were allowed to drop through and 
should cling to the perforated holes, they would cause the shell 
to jam and prevent it from rotating. When the perforated shell 
is removed from the die-holder, the shutter drops down of its 
own accord, thereby allowing the scrap punchings to drop out. 



294 PERFORATING DIES 

Perforating Shells of Tapered and Irregular Shapes. — In 

perforating shells of tapered and irregular shapes the same 
general methods of procedure as already described are used, 
with the exception that the die-holder is held in the die-bed at 
an angle of 5 to 70 degrees or more with the bottom of the die- 
bed, the angle depending on the shape of the shell and the per- 
forations to be made in it. In Fig. 8 is shown a die, die-holder, 
and die-bed for work of this kind. The angle at which the die- 
holder is set should be such that if the outer ends of the two 
extreme holes in the perforating die are connected by a straight 
line, this line would be parallel with the bottom of the die-bed, 
as indicated in Fig. 9, where the points A and B are on the line 
which should be parallel with the base of the die-bed. 

In Fig. 8 may also be seen the shell which is perforated by 
the die. The shell is rotated around the die by the tongue of 
the driving arbor engaging in an elongated hole in the bottom 
of the shell. The arbor is relieved at A in the usual manner to 
allow the scrap punchings to escape. No shutter is used, as the 
open end of the shell does not come near the scrap escape hole. 
The ratchet B, which is operated by a pawl, not shown, is keyed 
to the driving arbor, while the friction used for controlling the 
backlash bears upon the shoulder of the ratchet as indicated. 
This shell has two rows of perforated holes, fifty-two holes in 
each row. Eight holes at a time are cut, or four holes in each 
row. The reason that four holes in each row are cut at each 
stroke, instead of five, six, or eight, is, in the first place, that the 
number of holes cut at each stroke of the press must be such 
that the total number of holes in each row is a multiple of it. 
In the second place, it is not possible to get good results if the 
end punches are too far away from the center of the work, as 
these punches would strike a glancing blow. These holes would 
be somewhat elongated and "burry" instead of being clean, 
round, and free from burrs. In this case, four holes in each row 
is as much as is practicable. Of course, if the holes are small 
in diameter and close together, a greater number can be cut at 
one time than when they are larger and further apart. If the 
diameter of the shells is large, a greater number of holes can also 



PERFORATING TAPERED SHELLS 



295 



be cut at one time than with shells of smaller diameter, other 
conditions being equal. 

In Fig. 10 is shown another set of perforating tools set up in 
a Bliss press. These are used for perforating the sides of the 
tube shown at A with a series of rows of small holes. These 
tools are of a somewhat different type from those already de- 
scribed. No driving arbor is used, but the shells are rotated 
direct from the ratchet which is placed in front of the die-bed. 
There may be several reasons for using this construction : When 




Tools for Perforating Special Cylindrical Shells 



the bottom of the shell is to be left intact, no driving arbor 
can be used; sometimes the required shape of the shell is such 
as to prevent the use of a driving arbor; when the scrap punch- 
ings are so large and so numerous as to prevent them from 
dropping through if a driving arbor is used, or when that part 
of the shell that is to be perforated is very small in diameter, it 
may also be impossible to use a driving arbor. 

Referring again to Fig. 10, it will be seen that another set of 
perforating tools similar to the one set up in the press is shown 
to the left. This is used for perforating the shell shown at B. 
The ratchet and pawl are shown at C and D. The latter is 



296 PERFORATING DIES 

fastened to the dovetail slide E in the die-bed F. This slide 
is operated by the gate of the press by connection G. The hold- 
ing-on attachment consists of a slotted stud in the die-bed to 
which a swinging arm is pinned. A circular disk which revolves 
with the work is fastened to this arm, as is also the small handle 
directly in front of the attachment. Tins handle is used by the 
operator to swing the arm up and out of the way preparatory to 
removing the perforated shell from the die-holder. 

Methods of Rotating Shell to be Perforated. — A method com- 
monly used in connection with perforating tools for rotating the 
shell to be perforated is the dog-notch method. A dog C, 
Fig. 9, is fastened to the ratchet by screws or dowel-pins. The 
end of this dog fits a notch D in the shell, called the "dog- 
notch.'" The shell is slipped over the die-holder in such a man- 
ner as to cause the dog-notch in the shell to engage with the 
dog on the rachet. In this way the ratchet can index the shell 
directly around the die-holder. 

There are also a number of other methods used for rotating 
shells to be perforated. Besides those already described, one 
may make use of an irregular shaped hole in the bottom of the 
shell in connection with the driving arbor. Sometimes an ir- 
regular shaped hole is required in the bottom of the shell, and 
in such a case the tongue of the driving arbor may be made to 
fit this hole, which affords a good driving means. Sometimes 
use is made of a coaster brake device fastened to the ratchet. 
The tools used in connection with this device are similar to those 
already described, having the ratchet in the front of the die-bed, 
as shown in Fig. 9, with the exception that instead of using a 
dog, a device working on the principle of a coaster brake, such 
as is used on an ordinary bicycle, is fastened to the ratchet. 
With this device, no notch in the shell is required, as the open 
end of the shell is simply slipped into this device and given a 
part of a turn, causing it to be tightly gripped. The press is 
then tripped and the shell rotated around the die in the usual 
manner. In cases where a dog-notch is used and where there is 
a tendency on the part of the shell to slip in between the dog 
and the die-holder, which would prevent the shell from being 



PERFORATING TAPERED SHELLS 



297 



properly rotated, the die-holder is turned down as shown in 
Fig. 9, and the dog is made to just clear the holder. This pre- 
vents the shell from slipping in under the dog. 

The perforating die shown at H is held in the die-holder in the 
usual way, and is tapered lengthwise at a suitable angle as 
indicated. In order to afford a support for the die when in use, 
the bottom of the dovetail channel upon which the die rests is 
worked out so as to conform to some extent to the shape of the 
bottom of the die. This is done on dies where the holes are 
close together, so as to support the narrow bridges that separate 



BEARING FOR 
RATCHET- 




mmm 



^ 



Machinery 



Fig. 11. Die and Holder for Perforating Shell shown to the Right 

the irregular shaped holes in the die. The best way to do this 
work is to first work out an open space under the dovetail 
channel. This space is used for holding the scrap punchings 
that are prevented from dropping through by a shutter. In 
working out this space enough stock is left under the dovetail 
channel to support the die properly, as indicated in Figs. 9 and 
11, after which the openings through which the scrap punchings 
from the die drop are worked out. The shutter, which is shown 
closed in Figs. 9 and 11, swings open on the shutter pin as soon 
as the perforated shell is removed from the die-holder. 

The construction of the tools in Fig. 11 is similar to that of 
those just described. At the right is a plan of the die, showing 
the manner in which the die is tapered lengthwise, which in 
this case is six degrees on each side. When the tools shown in 



298 PERFORATING DIES 

Figs. 9 and 11 are in operation, two rows of holes are cut at 
every stroke of the press until the shell has completely rotated 
around the die and all the required rows of holes have been 
punched out. No device is used with these tools for holding 
the shells in place while they are rotating around the die, be- 
cause the position of the die-holder in the die-bed makes it easy 
for the operator to keep the shell in place. 

It sometimes happens that a perforated shell of the general 
type shown in Fig. 6 is required, with the exception that the 
bottom is left intact and therefore cannot be used in connection 
with a driving arbor for rotating the shell. In such a case, the 
shell is dog-notched and rotated in the manner already de- 
scribed, with the exception that the locating of the dog on the 
ratchet preparatory to perforating the shell forms an impor- 
tant part in the successful operation of the tools. The reason for 
this is that when cutting out the scallops of the shell the dog- 
notch C, Fig. 6, which is used for rotating the shell, must neces- 
sarily be cut away from the shell, and must, therefore, be placed 
in such a position that it will come in the center of the large 
scrap punching which will be cut out at the last stroke of the 
press, completing the operation. If the shaded portion shown 
at D is the punching resulting from the first stroke of the press, 
and if the blank is rotating from right to left, then the dog- 
notch must be located at C, central between the two scallops 
completed by the last stroke of the press, after the whole shell 
has been perforated. 

In order to prevent the punch A, shown in the upper right- 
hand corner of Fig. 12, which cuts out the scrap punchings D, 
Fig. 6, from coming in contact with the dog, a short slot is 
milled in the center of the face of the punch at the back end 
near the ratchet, so that the punch will clear the dog when that 
part of the shell containing the dog-notch is cut out. 

Lay-out of a Perforating Die. — Preparatory to laying out the 
die shown in Fig. 7, the die blank is carefully fitted to the dove- 
tail channel in the die-holder, after which it is turned up in the 
lathe in place and highly polished. It is then removed from 
the die-holder and blued by heating, and again driven into the 



LAYING OUT A PERFORATING DIE 



299 



die-holder, after which it is ready to be laid out. The die- 
holder is then mounted in the milling machine, the index-head 
in this case being set for twenty-eight divisions, as there are 
fourteen perforated holes of one design and fourteen of another. 
With a surface gage and by aid of the index head, the center- 
lines B and C are scribed. Line A is drawn merely to show the 





A^ 


B^ 


c' 








\- 


D 

\ 


-F 


(" 



< 


_5j 




l E 


\ 


1 j\ Cy 

A-T B-T C- 




10 D 


EG. 


V ^ ^>> 




Y///////////////\ 



,1 DEG, 




-10DEG. 



STRIPPER 




L_— ezzzzza 



Machinery 



Fig. 12. Perforating Punch and Die 

center of the die, and the center of each one of the holes in the 
die should be an equal distance from this line. Center-line D 
is next scribed the required distance from and parallel with the 
face of the die-holder. 

In laying out the hole on the center-line B a small circle of 
the exact diameter of the circular opening in the center is first 
scribed. The diamond-shaped ends are next laid out and scribed. 



300 PERFORATING DIES 

The star-shaped hole on the center-line C is laid out from a 
master punch which conforms to the required size and shape. 
In cases where the required number of shells to be perforated 
does not warrant the making of a master punch, the dies are 
laid out from the star-shaped punch that is used in connection 
with the die. 

In working out the die, the central hole from which the star 
design is made is first drilled and taper-reamed from the back to 
the size of the teat on the master punch, which is equal to the 
diameter of the circle passing through the bottom of the grooves 
in the star. The teat of the master punch is then entered into 
the die and the punch set and clamped to the die so that a point 
of the star is on line C. The outline of the punch is then scribed 
on the face of the die, after which the die is worked out and 
fitted to the punch. In order to facilitate matters, the punch 
is used as a broach after the die is filed to shape. In working 
out the other hole in the die, on line B, a hole is first drilled and 
taper-reamed from the back for the circular opening in the 
center. Two holes are drilled and reamed in the center of the 
diamond-shaped ends. The surplus stock between the drilled 
holes is then removed and the hole filed to the desired shape. 

There are two ways in which a die such as that shown in the 
upper left-hand corner of Fig. 12 may be laid out. One is to 
lay out the die on a milling machine in a manner similar to that 
already described. The other, which is most commonly used, 
is to lay out the die by scribing the design on its face from a 
master shell slipped over the die-holder which has the shape to 
be perforated worked out upon it. 

The master shell itself is kid out as follows: The shell is 
fastened to the die-holder by a few drops of soft solder to prevent 
it from moving. The die-holder is then mounted in the milling 
machine. The index-head in this case is set for twenty-four 
divisions. In Fig. 12 is shown the laying-out of the die, but 
the same method applies to the shell. With a surface gage used 
in connection with the index-head, the lines A, B, and C are 
scribed on the shell. Lines A and C represent the centers of 
two adjoining scallops, and line A is also the center for the two 



LAYING OUT A PERFORATING DIE 301 

holes / and H, while line B is exactly in the center between two 
scallops and constitutes the center-line for hole G. The lines E 
and D are next scribed on the shell, the former representing the 
height of the ears of the projecting scallops, while the latter 
shows the height at which the lower curved portions of the 
pointed scallops converge. After these construction lines are 
scribed on the shell, the design is readily laid out. The shape 
of the design is then worked out by drilling and the surplus 
stock is removed by means of a jewelry saw. The shell is then 
filed to the desired shape and when completed should be a 
duplicate of the portion cut out by the first stroke of the press, 
as shown at F in Fig. 6. In filing out a design, care should be 
taken to file out all the holes central with the center-lines A, B, 
and C, and also parallel with a plane passed at right angles to 
the center of the design, through the shell, in order that the 
holes may be at their exact required position on the inside of 
the shell. 

It will be noted in Fig. 12 that the large hole F in the die is 
extended past the line D; this is done in order to make sure 
that the large scrap punching D, Fig. 6, will be completely cut 
from the shell. This is especially necessary when the shells 
vary in length. The dotted line A, Fig. 6, is drawn so as to 
more clearly show the length of the twelve pointed scallops and 
their relation to the top of the shell. 

In drilling and working out the surplus stock in the die, Fig. 12, 
the same general methods that are used for working out an 
irregularly shaped blanking die are used. First, remove as 
much of the surplus stock as possible by drilling. When drilling 
out the surplus stock in the hole F, the smaller of the two cir- 
cular openings between the scallops is first drilled out and 
taper-reamed from the back to the finish size. After this, the 
hole is plugged with a small taper pin that is filed to fit it, and 
the large hole is drilled and taper-bored in a lathe. The round 
corners at the opposite end of the hole are then drilled out. 
These corners are left circular in order to add to the strength 
of the die and to prevent cracking of the die in hardening. The 
remainder of the hole is drilled and worked out in the usual 



\02 



PERFORATING DIES 



way. In working out the small holes G and //, the opposite 
ends arc first drilled and taper-reamed to the finish size, after 
which other holes are drilled and reamed and the surplus stock 
is removed with a small broach or jewelry saw preparatory to 
filing out the die. Hole / is drilled out ami the surplus stock 
removed in a similar manner. 

Filing Out the Die Shape. A the used for perforating the 
sides of cylindrical work is rather awkward to hold, either in 



Cvj^ 










i . 



o 



^ - H TAPPED ^ 



HOLES 



^ 



'4* 



<t& 



FOUR 

V SCREWS 




PERFORATING DIE 



SSSSS^ 



Machinery 



Fig. 13. Device for Holding Perforating Dies while Filing 

the vise or in die clamps, while being tiled out, owing to the fact 
that the face of the die is circular in shape and the sides are 
dovetailed. For this reason, a die-holding fixture, shown in 
Fig. E3, is used to hold the die in the vise, die-clamp, or tiling 
machine while it is being tiled out. The device shown is ad- 
justable to accommodate various widths of dies. The most 
essential points to be remembered when filing out a perforating 



PERFORATING PUNCH 303 

die are: Use a coarse file for the rough riling and finish with a 
smooth one. Take care to have the clearance riled straight 
in order to prevent the congestion of scrap punchings in the die; 
perforating dies as a rule are not very strong and are often 
cracked and broken because of neglect on this point. The 
clearance should not be filed over 1^ degree, in order to make 
the die as strong as possible; in cases where the holes in the dies 
are close together even less clearance is necessary, and a very 
narrow wall that separates two holes is filed almost straight on 
each side, with just enough of a taper to clear. Care must be 
taken when filing to prevent the back or the sides of the file 
from running into the finished part of the die. 

Making the Punch for a Perforating Die. — The punch used 
with the die shown in Fig. 7 is comparatively simple in its con- 
struction. It consists of the usual form of punch-holder into 
which the two perforating punches are driven. The star- 
shaped punch, after it is fitted to the die and hardened, is driven 
into the punch-holder in such a position that when it is entered 
into the die the sides of the punch-holder will be in a straight line 
and parallel with the die-bed. The tools are then set up in a 
hand or foot press so that the die and star punch are in proper 
alignment with each other. The foot treadle of the press is 
then disconnected from the gate so that the gate which holds 
the punch-holder in place can be withdrawn from the press 
without disturbing the punch-holder or the ways upon which 
the gate slides. The other punch, in its unfinished state, is 
then driven into the punch-holder and the face is coated with a 
jg-inch thickness of soft solder. The gate of the press is then 
slipped back into place and the impression of the outline of the 
die is transferred to the solder on the face of the punch. The 
punch-holder is then removed from the press and the punch 
driven out and milled to conform to the soft solder outline of the 
die, after which the punch-holder is put back into the press, care 
being taken to see that the star-shaped punch is in proper align- 
ment with the die. The milled punch is then put back in place 
and gradually sheared and fitted to the die. Each time after 
the punch has been lightly sheared into the die, the fins and 



304 PERFORATING DIES 

surplus stock are removed and the punch is again entered and 
sheared a trifle deeper, until it enters the die at least \ inch. 

The hand or foot press is very convenient to use when fitting 
perforating punches to their dies, because the construction of 
the press makes it possible to handle the gate conveniently and 
to keep the punches in proper alignment with the die. 

In making perforating punches such as shown in the upper 
right-hand corner of Fig. 12, the punch-holder is first machined 
to the desired shape and. size, after which the taper hole for the 
shank of punch A is reamed. The shank of the punch is then 
turned and fitted to the punch-holder and driven into place. 
The face of the punch is made to conform to the outside diame- 
ter of the shell and is then clamped to the face of the die and 
the outline scribed on it, after which it is milled to shape and 
sheared and fitted to the die. Before scribing the outline of 
the die on the face of the punch, care must be taken to see that the 
punch is set in the proper relation with the die, so that, when 
the finished tools are set up in the press, there will be no necessity 
for elongating or widening the slots in the die-bed used for 
clamping the die to the bed of the press, due to the punch not 
being laid out central with the die. 

After the first punch A has been fitted to the die, the holes 
for the other three punches are laid out so that the cutting part 
of the punches will be as nearly central with the shanks as pos- 
sible. Holes are then drilled and reamed for the shanks, and 
when this is done punch A is hardened. The reason that this 
punch is hardened before the other punches are fitted to the die 
is that if the punches were all sheared and fitted together and 
then punch A should spring in hardening, it would cause great 
difficulties in again bringing the punches into proper alignment 
with the die. After punch A has been hardened and driven 
back into the punch-holder, the shanks of the other three punches 
are turned up and fitted to the respective holes into which they 
are afterwards driven. The shanks of these punches may be 
made either straight or tapered, but should be a good driving 
fit and should have shoulders bearing against the punch-holder. 

Before the punches are driven into place, the die and punch 



STRIPPER OF PERFORATING DIE 305 

A are set up in the foot press and properly aligned with each 
other. The gate of the press is then withdrawn, the three 
punches are driven into place, and the faces coated with soft 
solder. The gate of the press is then slipped back into place 
and the outline of the die transferred to the punches, after 
which they are driven out and milled separately in the milling 
machine. Sometimes the punches cannot be driven out from 
the back of the punch-holder, because if the holes for these 
punches were drilled through they would run into and weaken 
the shank of the holder. In such cases holes are drilled from 
the side to meet the shank holes, in order to allow a taper drift 
to be used for starting the punch so that it can be removed. 

After the punches have been milled, they are driven back 
into the punch-holder and are sheared and fitted into the die, as 
previously described. The punches, of course, are lined up per- 
fectly with the die so as to enter into their respective holes as 
one single punch. After the punches are hardened they are 
sharpened by holding the punch-holder in a special grinding 
fixture and drawing the punches back and forth across the face 
of a wheel of about the same diameter as the shell to be per- 
forated. The bases of the punches are strengthened by milling 
the punches so that there is a liberal fillet between the shoulder 
of each punch and the milled-out shape. This also tends to 
prevent distortion in hardening. 

The Stripper of a Perforating Die. — The stripper serves three 
purposes: It strips the metal from the punch; it supports the 
small punches by preventing them from springing; and it tends 
to keep the perforated shell in shape by preventing it from 
bending or becoming "kinked up." The commonly used 
stripper construction is shown by the lower view, Fig. 12. The 
face of the stripper conforms to the outside diameter of the shell. 
It is drilled and worked out so that it is a sliding fit on the 
punches. The shoulder part of the stripper bears against the 
bottom lugs of the side pieces A and B, which are fastened to 
the punch-holder and prevent the stripper from being forced off 
the punch. Six spiral springs exert the required pressure on the 
stripper. When setting up the tools in the press, the stripper is 



3° 6 



PERFORATING DIES 



forced back about § inch and two pieces of, say, No. 31 drill rod 
are placed between the stripper and the bottom lugs of the side 
pieces, which keep the stripper out of the way while the punch 
and die are aligned with each other. 

Perforating dies of the type described are sharpened on uni- 
versal grinding machines. Owing to frequent sharpening it is 
sometimes necessary to raise them slightly by putting shims of 
sheet steel under the dies. These shims are drilled and filed out 
to conform to the holes in the dies, in order that the scrap 
punchings may drop through. 




Fig. 14. Type of Die Used for the Spiral Perforating Operation 

Spiral Perforating. — The die shown in Fig. 14 was designed 
to perforate shells similar to the one shown in Fig. 15, having 
holes extending along a spiral. It will be seen that the tool con- 
sists of a die-holder A, which is carried by the die-bed B. This 
die-holder is counterbored to receive the mandrel C and cam 
D which control the movement of the shell to obtain the de- 
sired location for the holes. An index ratchet E is keyed to 
the left-hand end of the mandrel and held in position by a nut 
F which holds it against the die-bed. This ratchet is operated 
by a pawl carried by the ram of the press. In order to 



SPIRAL PERFORATING 



3°7 



take up any backlash and secure accurate indexing, a spring 
pin G is provided. This pin enters counterbored holes in the 
ratchet, which are properly spaced to locate the holes in the de- 
sired positions in the shell; when the ratchet is moved on to 
the next station, the pin is 
forced back into the die- 
bed and then enters the 
next hole in the ratchet. 

The piercing die H is 
driven into the die-holder 
and the piercings are held 
inside the drum, until all 
of the holes have been 
punched, by means of a trap door 7. The shell is held in po- 
sition by nut / carried at the right-hand end of the shaft K. 
Cam D, which controls the movement of the shell, is secured to 
the shaft K by means of a key and pin. (This cam is shown in 
detail in Fig. 16.) Four pins M extend into the bore of the 









/^ = " % \ 




oj 


( ° ) 


o 


o ! 

i 


v_y 


o 


j 




Machinery 



Fig. 15. Shell having Spiral Perforations 




Fig. 16. Cam Used on Spiral Perforating Die 

die-holder and these pins are engaged successively by the cam 
D. The left-hand hole of a series is first pierced; the ratchet 
then rotates the shell and the action of the cam moves it to the 
right. The indexing is effected as previously described, one 
hole being pierced at each station. After the four holes on one 
spiral have been pierced and the ratchet starts to index for the 
next hole, the pin M slips over the point of the cam and the 
tension of the spring N then returns the cam and the work to 



;oS 



PERFORATING DIES 



the extreme left where the cam is engaged by the next one of 
the pins M. This process is repeated four times to complete 
piercing the holes on the four spirals in the shell. The longi- 
tudinal movement of the shell is limited by the pin L which fits 
in a slot in the shaft K. This die proved very satisfactory for 
this perforating operation. 

Tools for Clipping and Perforating Brass Shells. — Several 
interesting forms of press tools for performing clipping and 
piercing operations on brass shells are described in the following. 
Fig. 17 shows the shell ^4 which is to be clipped along the dotted 
line, and at B and C two views of the completed shell are shown. 
The die used for this clipping operation is illustrated in Fig. iS. 
The die .4, over which the shell slips, is a hardened steel collar 



























r \ 




f 




>> 




f 




>> 






A 






B 








C 








---"" 




























Machinery 



Fig. 17. Shell A to be Clipped along Dotted Line, and Two Views of 
Clipped Shell 

which is made to fit the shell accurately. This die is driven 
onto the stud B and held in place by means of the dowel-pin C. 
The stud B is a press fit in the die-bed and is prevented from 
turning by means of the key D which serves the additional 
purpose of locating the stud in the desired position. 

The clipping punches E are mounted on two dovetailed slides 
in the die-bed. This construction will be readily understood by 
referring to the cross-sectional view of the die-bed along the 
line X-X. Allowance is made for any adjustment of the punches 
that may be necessary on account of grinding by the provision 
of elongated holes for the screws which secure the punches to 
the slides. In case any adjustment is made, a shim of sheet 
steel of the required thickness is placed between the back of the 
punch and the slide. This gives the punch a bearing on the 
slide and relieves the screws from the pressure of the cut. The 
punches are made to conform accurately to the cutting edge of 



X-X NOIJL039 




^J 




3°9 






PERFORATING DIES 



dipping die. The faces of the clipping punches conform to 
the circumference of the shell and the points E cut a little in a 1- 
vance of the remainder of the punch in order to insure having 
the shell clipped without leaving a fin or burr of an}- kind. 

In order to clip a shell with this set of tools, the work is pla 
over the die and the press is then tripped. The punch shown in 
Fig. 10 is held in the ram by means of the shank A. When the 
ram descends, the inner surfaces B of the arms, which are in- 
clined at 30 degrees, come in contact with the steel pads J. 
Fig 18, in the slides that carry the clipping punches and m 




them in toward the die. This brings the dipping punches into 
action and causes the shell to be ekppef. When the rani starts 
its return stroke, the outer surfaces C ot the arms on the punch 
cause the slides which carry the capping punches tc 
turned to their original positions. It bt obvious that this 

method of actuating the slides is positive in action and does 
away with the use of springs for returning the slides. It will 
be seen that the punch-holder D. shown in Fig. 19, has a small 
piercing punch E mounted in it. This piercing punch is us* . 
in an operation that will be described later. When the tool is 
for the clipping ^ration, the piercing punch E and the 
punch-holder D are removed from the punch and the "hold- 



PERFORATING BRASS SHELLS 



.;n 



clown"' F is mounted in their place. This hold-down is held in 
place by means of a pin u which tits in the slot //. the length of 
the slot being sufficient to allow the hold-down the necessary 
amount of movement. This hold-down moves a little ahead of 
the clipping punches and thus comes into contact with the top 
oi the shell and holds it securely in plaee so that it cannot be 
raised off the die when the clipping punches begin to cut. 

Construction of the Die-bed. — The shells that are clipped or 
pierced on the die-bed shown in Fig. 18 are ordered in lots of 
not over 2S.000. This fact made it desirable to make a die-bed 



::> 





Fig. 20. Die Set up for Piercing Shell held in Vertical Position 

that could be used for both clipping and piercing operations, and 
this advantage is obtained by the design shown. This would 
not be of much advantage, however, if the work had been 
ordered in large quantities which would require the same set of 
tools to work day after day. In some eases, it was found de- 
sirable to provide special slides for a given set oi punches, and 
the clipping punches shown in place on the die-bed in Fig. iS 
are an example of this kind. When these punches are removed, 
the slides are taken off with them and the regular slides can then 
be put in place on the die-bed in order to allow other tools to be 
set up. It will be seen that gibs are provided to enable any 
wear which may develop in the slides to be taken up. 

The construction of the die-bed is such that shells can be held 



312 



PERFORATING DIES 



in either a horizontal or vertical position. This will be better 
understood by referring to Figs. 20 and 21 which show shells 
mounted in the vertical and horizontal positions. The shell C, 
which is shown in position on the die in Fig. 20, has five holes 
pierced in it. Two of these holes are pierced in either side of 
the shell by means of piercing punches carried in the slides of 
the die-bed, while the fifth hole is pierced in the top of the shell 
by means of the piercing punch E, which is shown in position 
in the punch-holder in Fig. 19. The piercing punches for work- 
ing on the sides of the shell are mounted in regular slides of the 



CO 




Machinery 



Fig. 21. Die Set up for Piercing Shell held in Horizontal Position 

die-bed shown in Fig. 18, Referring to the top view in Fig. 20, 
it will be seen that these punches are mounted in dovetail 
holders which are held in the desired position by means of keys 
A. The pins B locate the punches in their proper positions and 
are particularly convenient in obtaining the desired alignment 
when setting up the tools after they have been removed for 
sharpening. 

Fig. 21 not only shows the construction of the piercing die for 
piercing the shell C (shown at the left-hand side of the illustra- 
tion) but also illustrates the way in which the work is held in a 
horizontal position in the same die-bed that is used for holding 
work in a vertical position. Referring again to the illustration, 
Fig. 18, it will be seen that the part F at the back of the die- 
bed has a hole in it to receive the shank A of the piercing die- 



PERFORATING BRASS SHELLS 



3*3 



holder which is held in place by means of a set-screw. The shell 
C which is pierced on this die could be pierced in a vertical 
position but this would necessitate a three-slide die-bed. With 
the method now in use, the slot at either side of the shell is 
pierced by punches carried in the slides of the die-bed and the 
two small holes at the top of the shell are pierced by two punches 
carried in the punch-holder mounted in the ram of the press. 
In the case of the die used for piercing this shell, and all of the 
other dies referred to, it will be seen that a space is provided to 
allow the scrap and dirt to drop out at the bottom of the die. 



CHAPTER IX 
THE MULTIPLE PLUNGER PRESS AND ITS TOOLS 

The multiple plunger press is designed for producing, by means 
of a series of simultaneous operations, a complete article at 
every revolution of the press. It is constructed in various styles 
and sizes, the number of plungers ranging anywhere from three 
to eight. The most common type, however, and that most ex- 
tensively used for the general run of small work, is the one shown 
in Fig. i, which is a six-plunger machine. This machine can be 
used for such operations as blanking, cupping, piercing, forming, 
embossing, stamping, curling, bending, lettering, perforating, 
clipping, etc., and in fact almost any light operation that is per- 
formed on sheet metal. Of course this machine can be used 
when only three or more operations are required, by having the 
remaining plungers run idle. 

The machine is driven by tight and loose pulleys, as shown to 
the left of the illustration, and is back-geared; the ratio of the 
gearing is 4.5 to 1, the larger gear shown guarded to the left be- 
ing on the upper camshaft. This camshaft 5 is made from a 
crucible steel forging, while the cams held on it are made of 
tool steel and hardened. In addition to operating the plungers, 
this camshaft, through the gearing shown at G, operates the roll 
feed, the reel used for holding the metal being shown at H. The 
upper camshaft 5 also drives, through bevel gears, the vertical 
crankshaft /, which actuates the transfer slide and the lower 
camshaft Si. The plungers A, B, C, D, E, and F are made from 
tool steel of square section, and work in scraped bearings. The 
lower ends of the plungers B, C, D, E, and F are tapped out to 
receive the punch-holders, which are threaded into them. The 
blanking plunger A is bored out to receive a tapered split bush- 
ing into which the blanking punch is driven. The lower part of 
this split bushing is made square, so that, by turning it around 

314 



MULTIPLE PLUNGER PRESS 



315 



with a wrench, it can be removed and the blanking punch driven 
out. The blanking punch can also be made to fit directly into 
the plunger, if so desired. 

The blanking plunger A is set one-half revolution in advance 
of the other plungers, so that the blank, after it is cut, is carried 




Fig. 1. Multiple Plunger Press 



by the transfer slide over the first cupping die before the plunger 
B descends. This is accomplished by changing the position 
of the cam controlling the operation of the blanking plunger on 
the upper camshaft 5 in relation to the other cams. The 
plungers are operated by horizontal "lifters" L, one lifter being 
provided for each plunger. These lifters are clamped to round 
rods R located at the rear of the press, and knee pieces con- 
necting these rods to the plungers effect their operation. The 



316 MULTIPLE PLUNGER PRESS 

usual form of wedge adjustment is provided for increasing the 
pressure of the plungers, the adjustment being effected by means 
of wedges which lower or raise the " bumpers" as desired. 

The lower camshaft Si is provided with five cams M as shown, 
these being split and held to the shaft by screws, so that they 
may be shifted around on the camshaft to the position desired 
and then clamped. These cams operate the knock-up plungers 
into which are lightly driven the ejecting-pins used in removing 
the work from the dies. The work is carried from one die to 
the other by means of a transfer slide actuated by the vertical 
crankshaft /. 

Transfer Slide and Auxiliary Mechanism. — The transfer slide, 
or "carrier" as it is sometimes called, is made of tool steel, and 
is a sliding fit in the die-bed N. This slide holds the fingers, 
which are used for carrying the work from one die to the other, 
and also holds the nest or set-edge used in carrying the blank 
from the plunger A to plunger B, where the blank is cupped. 
A clear idea of the construction of a transfer slide, fingers, and 
dies can be obtained by referring to Fig. 2, where a plan of the 
slide and a sectional elevation of the dies and punches for pro- 
ducing a one-piece collar button are shown. The set-edge or 
nest is shown at A with the blank located in it. This nest may 
be removed and others substituted to suit the shape of the blank. 
It is cut out as shown, so that it will clear the first cupping 
punch when the slide recedes. 

The fingers B, C, D, E, and F, respectively, which are patented, 
are held in the transfer slide in smooth cylindrical bearings, the 
ends of the fingers being fitted into these bearings and held in 
place by screws G as shown. Each pair of fingers is actuated by 
coil springs H, which give them the desired tension on the blank, 
these springs being held in place by short pins driven into the 
lingers, and screws / located in the slide. The fingers are 
rounded at /, so that they will readily open when the slide 
recedes and the fingers slide past the punches. They are also 
rounded at the top and bottom as shown in Fig. 3, so that they 
will swing out of the way when they come in contact with the 
punch on the down-stroke or with the shell on the up-stroke. 




3 J 7 



3i8 



MULTIPLE PLUNGER PRESS 



The blanking die Ai is of rectangular section and is fastened 
by cap-screws and dowels (not shown) to the die-bed N, Fig. 2. 
The stock is placed on the reel H (see Fig. 1) and passes over a 




"1— <fiTT7a r 
SECTION ATX-Y 



Machinery, N. Y. 



Fig- 3- 



Illustration Showing the Construction of the Punches and 
Dies and the Manner in which they are Held 



lubricating sponge-box, and from there over the top of the 
blanking die in the usual manner. A pair of ratchet rolls located 
at the rear of the press and operated by the gears G on the upper 
camshaft 5 draws the stock over the die, after which it is wound 



TRANSFER SLIDE 



3*9 



into compact form on a scrap-reel, also located at the rear of 
the press. The blanking punch forces the blank, after it has 
been cut, through the die and locates it in the nest A. After 
the blanking punch comes out of the nest A, the transfer slide 
advances, carrying the blank, and locates it over the cupping 
die B h when the punch forces it out of the nest into the die. 
The blank, after being operated on, is removed from the dies by 
ejectors K which, in turn, are actuated by the cams M on the 
lower camshaft S\ (see Figs, i and 4). The ejecting-pins K 
which are lightly driven into the knock-up plungers, when not 
being forced down by the punches, are retained flush with the 
top face of the dies, by means of flat springs S%, which are shown 




% !! 



*9^Mrf4* 



COT 




Machinery, N. Y, 



Fig. 4. The Knock-up Plunger and the Method of Operating and 
Retaining it 

in Fig. i and in detail in Fig. 4. These springs fit over bronze 
plugs B, which bear against the knock-up plungers P. The 
bronze plugs B are provided with a teat T which fits in a slot 
cut in the plunger, thus preventing them from turning. The 
springs are held in position by cap-screws, and are provided with 
elongated holes, which fit over the reduced ends of the bronze 
plugs. The knock-up plungers are of square section on the 
lower end, and rounded so that they work freely on the lifting 
cams M. A hole H is drilled in the top of the plungers into 
which the ejecting-pins are lightly driven. 

Operation of the Transfer Slide. — In operation, as the stock 
is drawn by the feed-rolls over the blanking die, it is blanked, 
and the blank is forced through the blanking die Ai into the nest 
A, Fig. 2. When in this position the transfer slide advances, 



320 MULTIPLE PLUNGER PRESS 

and carries the blank from the die A\ to the cupping die B\. 
Here the slide dwells until the cupping punch descends and 
forces the blank through the nest A into the die. The transfer 
slide now retreats before the punch has ascended out of the die, 
and for this reason it is necessary to cut out the nest as shown, 
so that it will slip by the punch. When necessary, the punch is 
reduced in diameter just above the working part in order that 
the nest can slip past it. On the up-stroke of the plunger B 
(see Fig. i), the ejecting-pin K, Fig. 2, which is held in the 
knock-up plunger P, Fig. 4, forces the cup out of the die Bi 
into the ringers B; then, as the slide again advances, the linger 
B carries the cup to the die C\, this order of operation being 
continued in a similar manner until the fingers F carry the 
finished piece to the last die F 1} after which it is forced out of 
the fingers and passes out of the chute K (Fig. 1) into a box. 
It can therefore be seen that the work is at all times under 
perfect control, the ejecting-pin K and the fingers working in 
unison. 

After the work has been operated upon for the last time by 
the punch in plunger F, and when the operation is a clipping or 
redrawing operation, the work readily drops into a box; other- 
wise, if some other operation is to be performed, the work is 
ejected by means of compressed air or some other simple eject- 
ing device or fixture. The successive operations on the one- 
piece collar button are shown directly under the dies for pro- 
ducing them in Fig. 2, the operations being designated by the 
letters A% to F 2 , inclusive. 

Method of Holding the Punches and Dies. — As previously 
stated, the cupping and stripping punches are held in punch- 
holders, which are screwed into threaded holes in the plungers. 
This is more clearly shown in Fig. 3, where the punch is shown 
held in the manner referred to. The punch shown here is the 
one located in plunger C, Fig. 1, and is used for performing the 
operation C 2 on the collar button shown in Fig. 2. The punch 
A (Fig. 3) is made of the desired shape and is driven into the 
holder B, this holder being provided with an octagon head and 
threaded on the upper end so that it can be screwed into the 



MULTIPLE PLUNGER PRESS TOOLS 321 

plunger. A push-pin C, for the punch A, is operated by a coil 
spring D, which is retained in the holder B by a headless screw 
E. This push-pin, however, is not used on all of the punches, 
other types of stripping fixtures being employed. For this class 
of work, the fingers are shaped as shown at F, so that they hold 
the cup by the flange alone, not touching the body of the cup 
at all. This holds the cup effectively, as the ejector-pin K is 
always in the up-position, except when being forced down by 
the punch A, thus additionally supporting the cup while in the 
finger and preventing it from tipping. The manner in which 
the ejecting-pin K is held in the knock-up plunger P is also 
clearly shown in this illustration. 

The die / is driven into a tool-steel die-holder J, this holder 
being counterbored as shown, so that the die fits up against the 
shoulder, preventing it from being drawn out. The die / rests 
on a hardened tool-steel washer R located in the die-bed, and 
which resists the thrust of the punches. The die-holder J is 
fitted in a dovetailed groove formed in the die-bed, and is re- 
tained in the desired position by means of set-screws L located 
in blocks M, which are held to the die-bed by means of cap- 
screws N. The set-screws L are provided with lock-nuts O, 
which lock the screws in the desired position. 

These machines work so successfully that they require very 
little attention. In fact, they will sometimes run for weeks at 
a time without requiring any special attention beyond that of 
oiling, starting in a new coil of metal, and occasionally sharpen- 
ing and polishing the punches and dies. 

Tools for Multiple Plunger Presses. — The multiple plunger 
press has become a most important factor in the economical 
manufacture of articles from sheet metal, and this type of press 
is now used for both large and small work; the presses for the 
large sizes of work are necessarily of stronger and more massive 
construction than those used for smaller work. The tools 
illustrated and described in the following are used for the smaller 
classes of work. 

Before going into details concerning the construction of the 
punches and dies used in multiple plunger presses, it may be well 



322 MULTIPLE PLUNGER PRESS 

to lay stress upon the fact that, preparatory to constructing the 
tools, one of the first things to do is to make sure that the con- 
struction of the press is such that the tools will not only be in- 
terchangeable in a given press, but also with the tools in other 
presses. In trying out a new set of tools, it is often found that 
better results are obtained by changing the sequence of some of 
the operations; for instance, if plunger No. 2 does the cupping, 
No. 3 the forming, No. 4 the piercing, etc., it often happens that 
some of these operations must be reversed, and if the tools are 
interchangeable, this can be done without any extra time being 
spent in altering the length of the punches, or in making new 
ejecting-pins to fit the press. Moreover, if the tools for differ- 
ent presses are not interchangeable, they can only be set up and 
run in the press for which they were originally made; this 
means that some of these presses may frequently be out of use, 
simply because there are no orders for work which calls for the 
use of the tools that were made for the "dead" machine in 
question. On the other hand, there may be orders for work 
which must necessarily wait until another job has been run 
through on a given press that is in use, because the tools to be 
used were made for the press that is already in use, and are not 
interchangeable. This deplorable condition actually exists in 
some shops. The fact must be taken into consideration that 
the taper wedges used for adjusting the stroke of the plungers 
affords only ^ inch adjustment, and unless the presses are made 
so that the tools are interchangeable, the loss of time due to 
having "dead" machines is bound to occur again and again. 

In adjusting a multiple plunger press to insure interchange- 
ability, the first thing to do is to regulate the taper wedges used 
for adjusting the stroke of the plungers, so that they will all be 
in the same relation to each other. The press is then given a 
half turn, so that all the plungers except plunger No. 1 are 
down as far as they will go, so that the distance from the top of 
the die-bed to the face of the respective plungers can readily be 
measured. It seems hardly necessary to say that this distance 
must measure the same in each case. The same can also be 
said of the face of the knock-up plungers which, when raised 



EXAMPLES OF MULTIPLE PLUNGER PRESS WORK 323 



up as far as they will go, must all measure the same distance to 
the top of the die-bed. The depth of the ejecting-pin holes in 
these plungers must also be the same, as, on small work, the 
ejecting-pins rest on the bottom of these holes; and it is there- 
fore essential that the depth of the respective holes be the same 
if the ejecting-pins are to be interchangeable. It is also impor- 
tant to have the holes for the dies in the dovetail die-holder 
perfectly central with the threaded holes in the plungers, and also 
bored out to fit plug standards, so that there will be interchange- 
ability so far as the various dies and die-holders are concerned. 




Machinery 



Fig. 5- 



Construction of Punches and Dies and Successive Operations in 
Drawing and Piercing Shell F 



Examples of Shell Work done on Multiple Plunger Press. - 

Fig. 5 shows a set of tools for a six-plunger press used in making 
the shell which is shown completed at F. The diameter of this 
shell is 0.270 inch, the length is \ inch, and it has a small elon- 
gated slot pierced out of the bottom. The metal is first fed be- 
tween the guide plates, where the round blank A is punched out 
and forced into the nest G in the transfer slide by the blanking 
punch in plunger No. 1 ; the nest is made to fit the blank tight 
enough to retain it. The blank is then carried under the draw- 
ing punch held in plunger No. 2 and drawn up into the shell 
shown at B. The punch is made small enough so that it will 
just draw up the shell and keep it from wrinkling, thereby 
preventing the metal from becoming too hard to be successfully 
worked in the following operations. After the shell is drawn 
up, it is ejected from the die by the ejecting-pin H and then 
forced between the fingers in the transfer slide. These fingers 



3 2 4 



MULTIPLE PLUNGER PRESS 



hold the shell in place while it is being carried under plunger 
No. 3. As the shell B does not hug the punch tightly, no stripper 
is necessary; the push-pin prevents the shell from clinging to 
the punch. When the shell B comes under plunger No. 3, it is 
redrawn to the shape and size shown at C, care being taken to 
have the redrawing punch small enough so that it will not pinch 
the metal any harder than is absolutely necessary. The same 
can also be said with reference to the following drawing oper- 
ations, except the one done under plunger No. 5, which draws 




O 



E 



C-yA 




it* u 



s^O 



Q ® 



Machinery 



Fig. 6. Stationary Stripper and Method of Securing it to the Press 

the shell E hard. The last operation is piercing out the narrow 
slot in the bottom of the shell, which is done by the piercing 
punch held in plunger No. 6 and the piercing die shown directly 
underneath it. The finished shell is then pushed from the press 
into a pan or box by a push-finger held in the transfer slide. 
It will be seen that no ejecting-pin is used in this operation, as 
the shell rests on the top of the piercing die while being pierced, 
and therefore the knock-up plunger can be removed in order to 
allow the scrap punchings to escape. In stripping the shell from 
the punches in the third, fourth, fifth, and sixth operations, 
stationary strippers similar to the one shown in Fig. 6 are used. 
Stripping the Work from the Punches. — For the punches and 
dies used in a multiple plunger press, two forms of strippers are 
generally used. One of these strippers is known as the station- 
ary stripper, while the other is called a traveling stripper and is 



EXAMPLES OF MULTIPLE PLUNGER PRESS WORK 325 



used in connection with a thimble for stripping the work from 
the punches. Fig. 6 shows the stationary stripper A held in 
position by the stud B, which, in turn, is held by a bracket C 
fastened to the rear of the press. The stripper has an elongated 
slot in one end to provide for adjustment. In addition to the 
stud B, the stripper is supported by the pointed screw D and the 
screw E, which are placed on each side of the hole used for 
stripping the shell F from the punch G. These screws, as well 
as the stud B, can be adjusted to different heights to accommo- 



O 




rl/' 



I- 



u 




1 



a 







Machinery 



Fig. 7. Illustration Showing Use of a Traveling Stripper on a 
Multiple Plunger Press 

date different lengths of shells. The pointed end of the screw 
D rests in a small countersunk hole in the stripper; this not 
only helps to stiffen the stripper but also tends to prevent it 
from shifting endways. Fig. 6 illustrates the manner in which 
the stripper strips the shell shown directly underneath it. The 
device used for stripping flanged shells from the punch with a 
stationary stripper is shown in the upper left-hand view. Two 
short shouldered pins H strip the work from the punch, so that 



;26 



MULTIPLE PLUNGER PRESS 



the flanged part of the shell can be readily grasped and retained 
in the circular grooves in the fingers I , as shown. These pins 
are made small and placed in the center of the open space be- 
tween the fingers so that the projecting pins will clear the fingers 
and not interfere with their free action. The sectional view of 
this stripper is on the line X-X. 

Fig. 7 shows the manner in which a traveling stripper is used 
in the multiple plunger press for stripping the work from the 
punches. The punch is made a sliding fit in the stripping 




ic3 ,« 



TZT TJ 

E D 



Fig. 8. Example of Flanged Work Formed on Six-plunger Press 

thimble A , which has a circular groove that engages in the forked 
part of the traveling stripper B\ this thimble is also used in 
forming up flanged shells, as the face of the punch-holder C 
forces the thimble down on the flange and keeps it flat, thus pre- 
venting the work from getting out of shape. Making use of 
the stripper thimble in this manner does away with the necessity 
of using a solid shouldered punch; and as these thimbles can 
be used over and over again, they effect quite a saving. When 
in operation, the thimble is forced downward by the punch- 
holder; on the upward stroke of the press the traveling stripper, 
which acts in the capacity of a flat spring, forces the thimble 
upward with the assistance of the knock-up plunger D. When 



EXAMPLES OF MULTIPLE PLUNGER PRESS WORK 327 

the fork of the stripper comes in contact with the adjustable 
stop E, as shown, it affords a substantial stripping arrangement 
for stripping the shell F from the punch. The stop E is fastened 
to the front of the press, and is made adjustable to allow for 
different lengths of shells, in order that the shells can be stripped 
from the punches at the right time on the upward stroke of the 
press. The punch is made slightly tapering so that the shells 
can be readily pushed off by the push-pin G and grasped by the 
ringers H in the transfer slide I. 

Examples of Flanged Shell Work. — Another interesting ex- 
ample of shell work, as performed on the multiple plunger press, 
is shown in Fig. 8. These tools complete the shell shown at F 
in six operations, their construction and operation being some- 
what similar to the tools described in connection with Fig. 5. 
The metal is fed under stripper G in the usual way, and guided 
by the plates H; I is the blanking die and J the nest in the 
transfer slide for carrying the blank under plunger No. 2, where 
it is forced into the die and cupped up as shown at B. In this 
operation no blank-holder is used to prevent the blank from 
puckering while it is being drawn up. On the downward stroke 
of the press, the cupping punch forces the blank and the eject- 
ing-pin K downward. As the knockout plunger L which holds 
the ejecting-pin in place is held up by spring tension, the blank 
is prevented from shifting and is held central while being cupped 
up. The blank is first partly cupped by the round corners 
shown on the top of the die, after which it is drawn up into the 
desired shape by the lower shoulders on the die. On the up- 
ward stroke of the press, the ejecting-pin forces the cupped shell 
out of the die into the fingers of the transfer slide. No stripper 
is required, as the metal is not pinched hard by the punch, and 
the shell therefore does not hug the punch. The push-pin M 
merely prevents the shell from clinging to the punch on account 
of any settlement of oil in the bottom of the shell. In cupping 
up the shell in the manner previously described, it should be 
stated that a clean cut blank must be used which is free from 
all burrs, as otherwise the shell will pucker and wrinkle while 
being drawn into shape, inasmuch as no blank-holder is used. 



328 



MULTIPLE PLUNGER PRESS 




After the shell is 
cupped, it is trans- 
ferred under punch 
No. 3, where it is 
drawn up and 
flanged as shown at 

C. Punch No. 4, 
with the aid of the 
thimble N, draws 
the barrel part of 
the shell smaller and 
longer, as shown at 

D, while punch No. 
5 acts upon the 
flanged part of the 
shell only, and forms 
it into the shape 
shown at E. The 
teat of this punch is 
made a sliding fit in 
the barrel part of 
the shell and guides 
it into the die. As 
the shell does not 
hug the punch, no 
stripper is neces- 
sary; the push-pin 
O prevents the shell 
from remaining on 
the punch. The last 
operation is to pierce 
out the ^-inch hole 
in the shell bottom, 
shown at F; this is 
done by punch No. 
6, after which the 
fi. n i s h e d shell is 



EXAMPLES OF MULTIPLE PLUNGER PRESS WORK 329 

stripped from the piercing punch by a stationary stripper. The 
work is then either blown out of the way by compressed air, 
or pushed off the press by a push-finger, and drops into a box 
under the press. 

Example of Shell Work on Eight-plunger Press. — Fig. 9 
shows a most interesting set of tools for making the shell shown 
at H complete from sheet metal on an eight-plunger press. 
The tools shown are made and operated in the same manner as 
those already described and therefore require very little ex- 
planation. The illustrations show the progress of each oper- 
ation very clearly, as the shell is carried from one punch to the 
other. The blank A is cut from the metal, carried under punch 
No. 2, and cupped up in the usual way. The cupped shell B is 
then transferred and gradually drawn up into a flanged shell as 
shown at C, D, and E. In drawing up the shell to the form shown 
at D and £, the usual stripping thimbles are used- in connection 
with traveling strippers. On the next operation, punch No. 6 
cups the flanged part of the shell into the shape shown at F. 
The teat of punch No. 6 next engages the inside of the shell and 
forces it into the die. As the shell is drawn into the die, the 
flanged part is cupped up while being drawn over the corner of 
the die which is slightly rounded, after which it is formed into 
the desired shape by the beveled shoulder of the die. Punch No. 
7 pierces the bottom of the shell; the shell is then stripped from 
the punch by the stationary stripper. On the last operation, 
the bottom end of the shell is flared outward, as shown at H, by 
being forced over the short tapered teat shown in the center of 
the die. The shell is then stripped from the punch and drops 
into a box under the press. 



INDEX 



Page 

Air blast, use of, for ejecting press work 

Air pockets in dies, formation of *3° 

"Alligator skin " effect on drawn parts 

Angle of redrawing die, drawing edge 

Angular clearance for dies 

Annealing dies, value of 

Annealing drawn shells 

Armature disks, making sectional dies for 26 ~_ 2 8? 

Automatic press feeding mechanisms 2 ° 267 

Automatic release for feed-rolls . 

Baths for cooling dies when hardening 

Bending and twisting die, combination ■ J°° 

Bending dies ""'...... 190! 201 

compound type 

for forming staples 

for making five bends 

for making four bends ig ~ 

simple types of ■ , ■ ■ ■■ ■ ■ • ■ • "121-130 

Blank diameters, determining, for drawn work I27 - I 2o 

formulas for drawn shells 

table of, for cylindrical shells 

Blanked holes, amount of stock between 94 

Blank-holder, arranged to prevent excessive flange pressure .... ■ - • • 107 

hand-operated type, for single-action press 

of double-action die jg 

of inside type for redrawing die ^_ 

pressure compensating attachment for 

Blanking and piercing dies, examples of ^ 

Blanking and shaving dies, combination ^ 

Blanking die, laying out ^ 

location of stop-pin 

machining opening in 2 

of plain type ^6 

Blanking die templets ^g 

Blanks, for elliptical shapes ^ 

for rectangular flanged shells 

for rectangular tapering shells 

for rectangular work, shape of 

sub-press die, separating from scrap 

33* 



332 INDEX 

Page 

Bolsters or die-beds, types of 96-103 

Bridge between blanked holes, width of 94 

Bridge type of stop-pin 84 

Burnishing before perforating shells 288 

Burnishing die 10 

Cam-actuated strippers 77 

Cartridge cases, drawing 150 

trimming to length '. 157 

Chute and hopper feed 280 

Chute feed for drawing press 282 

Clamp for diemakers _ 38 

Classes of dies 1-24 

Clearance, angular, for dies 51 

at corners of rectangular drawing dies 171 

between punches and dies 49 

for first-operation drawing die 119 

Cochrane-Bly filing machine for dies 47 

Cochrane-Bly universal die shaper 43 

Combination die, equipped with special blank-holder 167 

for deep drawing 167 

pressure compensating attachment 165 

why used for shallow work no 

Combination drawing die 13 

Compensating attachment, pressure, for blank-holder 165 

Compound bending dies 190-201 

Compound blanking dies 6 

Compound dies, points on making 80 

Cooling baths for die hardening 69 

Crab-clamp for diemakers 38 

Curling dies 20, 204 

for edges of tin buckets 209 

for making hinges 204 

special design for typewriter part 209 

for small brass covers 211 

Cyanide of potassium, use of. when hardening 184 

Cylindrical hub drawn from pierced hole 1 83 

Depth of first drawing operation 111 

Diameter of first drawing die in 

Diameter reductions of drawn shells 112 

Diameters of blanks for drawn work 1 21-130 

Die-beds or bolsters, types of 96-103 

Die diameter for first drawing- operation in 

Die diameter reductions for redrawing 112 

Die filing machine, Cochrane-Bly 47 

Diemakers' adjustable clamp 38 



INDEX 333 

Page 

Dies, bending, simple types of 19, 188 

blanking, laying out 2 7 

burnishing IO 

combination drawing J 3 

compound, points on making 8o 

compound type ° 

correcting mistakes made in machining 74 

curling 2 °> 2 °4 

different classes of I-2 4 

drawing "> IO ° 

drawing, clearance for first-operation 1 IO - 

drawing, for cylindrical shell J 34 

drawing, for spherical covers *35 

drawing, for tin nozzles x 37 

drawing, shapes of edges IX 5 

embossing 10, 147 

examples of sectional construction 244-258 

follow, tandem or progressive 3 

for blanking and piercing, examples of io 3 

formation of air pockets in l 3° 

for perforating tapered and irregular shapes 294 

for washers, laying out S3 

gang or multiple 5 

hardening 

hardening, cooling baths for °9 

hardening, when operation is required • 74 

location of stop-pin °4 

perforating type : 7» 28 7 

plain blanking 2 

reworking worn 75 

shapes of edges for redrawing Il8 

• R 

shaving or trimming 

shear of cutting faces °4 

sub-press, construction and use of 2I2 

sub-press, general methods of constructing 226-236 

sub-press type and its advantages 21,212 

swaging > 2 4 

types of die-beds or bolsters for 9 6_I °3 

types of stop-pins for 8l_ 93 

used in multiple plunger presses 3 21 

Double-action dies I $ 

Double-roll feeding attachment • 2 °9 

Drawing and forming die construction, miscellaneous points 181 

Drawing and forming, lubricants for r 3 r 

Drawing, cause of stock thickening IIQ 

formation of wrinkles in x z 4 

rectangular, amount of reduction between draws x 74 

rectangular, determining depth for first-operation J 72 



334 INDEX 

Page 

Drawing, rectangular, shape of blank for 174 

Drawing a brass shrapnel case 159 

Drawing a cylindrical hub from a pierced hole 183 

Drawing, blanking, and embossing die 147 

Drawing cartridge cases 150 

Drawing deep parts in combination die 167 

Drawing dies, classes of 11-18 

clearance for first-operation 119 

diameter for first-operation : 1 1 1 

diameter formulas 113 

for cylindrical shell 134 

for flanged taper shell 140 

for rectangular work 164 

for spherical covers 135 

for tin nozzles 1 37 

ironing stock in 120 

length of straight or cylindrical surface 182 

of indexing type, multiple 159 

of sub-press type 219 

radius of drawing edge 117 

rectangular, determining number of drawing operations 172 

rectangular, how corners of first and second dies should be laid out 173 

rectangular, laying out 1 7° 

rectangular, radius of corner of first-operation die 173 

rectangular, radius of drawing edge 17 2 

rectangular, with inserted corner pieces 169 

selecting type of i°9 

special, for single-acting press 144 

Drawing edges for first-operation dies 115 

Drawing edges for redrawing dies 118 

Drawing, forming, and blanking die 145 

Drawing in multiple plunger press 3 2 3~3 2 9 

Drawing reductions for successive operations 1 1 2 

Drawn shell, causes of fractured bottom 182 

Edge of drawn shell, cause of unevenness 117 

Edges of first-operation drawing dies 115 

Edges of redrawing dies 118 

Ejecting press work with air blast 2 84 

Elliptical shapes, blanks for drawing 178 

Embossing, blanking, and drawing die : 147 

Embossing dies 1°, *47 

Emergency dies 2 5 

Feed chute for drawing press 2 82 

Feeding mechanisms for presses, automatic 265-282 

Feed-rolls, automatic release for 267 

Filing blanking dies by hand 45 



INDEX 335 

Page 

Filing machine for dies 47 

Filing perforating die openings 302 

Fitting punch to die 51 

Follow die 3 

equipped with trimming punch 108 

locating punches in ■ 62 

Forming and drawing die construction, miscellaneous points 181 

Forming dies 18 

method of locating punch relative to 185 

Formulas for blank diameters 127-129 

Fractured bottom of drawn shell, causes of 182 

Friction dial and push feed 277 

Friction dial and reciprocating feed 279 

Friction dial feed for press 277 

Gage plates, method of securing, to dies 185 

Gang die 5 

Grain of steel, relation of, to bends 183 

Hardening dies 66 

cooling baths for 69 

determining hardening temperature 67 

drawing temper of 71 

points on method of heating . . . . . . . . . 71 

when hardening operation is required 74 

Hardening punches 72 

when operation is required ' 74 

Heating die, points on 71 

Hub, cylindrical, drawn from pierced hole 183 

Inclined press, die-bed for 98 

Indexing type of drawing die 159 

Ironing stock in drawing 1 20 

Ironing stock in drawing rectangular parts 1 70 

Knockout for a punch-press 282 

Latch type of stop-pin for dies 85-92 

Laying out a perforating die 298 

Laying out blanking dies 27 

Laying out blanking die from templet 38 

Laying out blanks for elliptical drawing 178 

Laying out blanks for rectangular drawing 174 

Laying out washer dies 33 

Locating punches in follow dies 62 

Locating punches in punch-holder 61 

Lubricants for drawing and forming 131 



336 INDEX 

Page 

Machine steel, use of, for making punches 26 

Magnetic device for die hardening 67 

Milling machine for dies, Thurston 44 

Multiple die 5 

Multiple drawing die of indexing type 159 

Multiple plunger press, arrangement of 314 

examples of flanged work 327 

example of shell work on 321 

tools or dies used in 321 

Perforating die stripper 305 

Perforating dies 7, 287 

equipped with tools for trimming 308 

filing the openings 302 

for cylindrical work 287-293 

for spiral perforations 306 

for tapered and irregular shapes 294 

methods of laying out 298 

methods of rotating work 296 

Perforating punches, cause of breakage 78 

method of making 303, 304 

Piercing punches, types of 58 

Pilot on punch, size and shape of 78 

use of 4 

Pneumatic press attachment for ejecting work 284 

Pratt & Whitney vertical die shaper 41 

Press feeding mechanisms, automatic 265-282 

Press, mechanically-operated knockout for 282 

multiple plunger, dies used in 321 

multiple plunger, example of shell work on 321 

multiple plunger, stripping work from punches 324 

multiple plunger, tools for 321 

multiple plunger type 314 

Pressure-pads or blank-holders 13, 114 

Pressure-pads, rubber 187 

Progressive or follow type of die 3 

Punches, cause of lateral thrust 80 

fitting to die 51 

forming, method of locating 185 

for perforating die, method of making 303 

hardening 7 2 

hardening, when operation is required 74 

how stock is stripped from 75 

locating in follow dies 62 

locating in punch-holder 61 

methods of holding 53 

perforating, cause of breakage ■ . 78 

perforating, method of making 304 



INDEX 337 

Page 

Punches, piercing, types of 5& 

points to consider when locating So 

shear of cutting faces °4 

tempering 73 

trimming, for follow die Io8 

variation in length of multiple 79 

Punch-holder 54 

Punch plate 54 

Punch press, mechanically-operated knockout for 282 

Punch troubles and remedies 7$ 

Push feed for drawing press 2 73 

Quill punches 6o 

Rack-and-pinion double-roll feed 2 7° 

Radius of drawing die x : 7 

Ratchet dial feed, for press 2 73 

safety device for 2 75 

Ratchet type of roll feeding mechanism 26 5 

Rectangular drawing, amount of reduction between draws 174 

determining depth for first operation J 7 2 

method of reducing stock thickness x 7o 

shape of blank for x 74 

Rectangular drawing dies l6 4 

clearance at corners I?I 

determining number of drawing operations I 7 I > x 7 2 

equipped with inserted corner pieces l6 9 

how corners of first and second dies should be laid out *73 

laying out I7 ° 

radius of corner of first-operation die J 73 

radius of drawing edge •. I72 

Rectangular drawn parts, trimming : l8 ° 

Rectangular flanged shells, blanks for x 77 

Rectangular tapering shells, blanks for *77 

Redrawing dies I7 

shapes of edges for • Il8 

Reductions in successive drawing operations II2 

Rubber pressure-pads .' J 7 

Safety device for ratchet dial feed 2 75 

Sectional die construction, examples of 244-258 

Sectional die, for linotype type-bar plates 2 5 2 

for square washers 247 

grinding the parts of 2 59 

Sectional type of sub-press die 22 3 

Shaping and slotting machines for dies 4 1 

Shaving and blanking operation combined Io6 



$yo INDEX 

Page 

Shaving die 8 

nest of spring-operated type for 240 

Shear of punch and die faces 64 

Shearing punch into die 51 

Shrapnel case, drawing a brass 159 

Single-roll feed for punch press 265 

Slide feeding mechanism for press 273 

Slotting and shaping machines for dies 41 

Solder, use of, on punch when fitting : $2 

Spherical cover drawing dies 135 

Spiral perforating die ^06 

Staple bending die I0 7 

Steel, for deep rectangular drawing 170 

grain of, in relation to bends 183 

Steel used for dies 26 

Stock, amount of, between blanked holes 94 

Stoning a blanking die 48 

Stop-pin, bridge type 84 

classes of, for dies Si-96 

latch form, operated by stock 87 

plain fixed type 82 

position of, relative to die opening 94 

positive heel-and-toe latch type 91 

side-swing latch type 90 

simple latch form 85 

spring-toe latch type 89 

starting, for follow die 93 

Stripper attached to punch 76 

Strippers, cam-actuated type 77 

Stripper of a perforating die 305 

Stripper pins for drawing dies 159 

Stripping blanks that adhere to punches 242 

Stripping stock from punch 75 

Stripping stock uniformly, importance of 79 

Stripping work from punches of multiple plunger press 324 

Sub-press, amount that punch enters dies 23 

axial grooves in plunger and barrel 226, 229, 236 

construction and use of 212 

construction of the four-post or pillar type 237 

for drawing shallow cups 219 

form of large sizes 221 

general methods of constructing 226-236 

method of babbitting 232-234 

sectional construction 223 

typical construction 213 

use of, and advantages 21, 212 

Sub-press die blanks, separating from scrap 243 

Swaging die 24 



INDEX 339 

Page 

Tandem or follow type of die 3 

Taper shell drawing 140 

Temper of die, drawing 71 

Temperature for die hardening 67 

Temperature range for hardening 68 

Tempering punches 73 

Templet method of laying out die 38 

Templets for blanking dies 36, 

Thurston undercutting die milling machine 44 

Transfer slide or carrier of multiple plunger press 316 

Trimming drawn rectangular parts 180 

Trimming punch for follow die 108 

Triple-action dies 16 

' Twisting and bending die, combination 200 

Undercutting die milling machine, Thurston 44 

Universal die shaper, Cochrane-Bly 43 

V ent holes in dies 130 

Washer dies, laying out ^^ 

Wiring dies for small brass covers 211 

Worn dies, method of reworking 75 

Wrinkles, formation of, in drawing 114 



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